VEDHA

What is PAR? Lighting & Brightness Explained for Planted Tanks

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17 March 2025

There are tons of different types of aquarium lights available to hobbyists, but how do you know which one to choose for your aquarium? One important question to ask is whether or not the light source is bright enough to grow the aquarium plants you’re looking to get. Let’s talk about PAR as a helpful determining factor when choosing your next planted tank light.

Defining PAR

PAR is simply an abbreviation for Photosynthetically Active Radiation (sometimes referred to as Photosynthetically Available Radiation). It quantifies the brightness levels of light that are used by plants in order to grow. If you have heard of lumens, this is a similar concept. The difference is that lumens describes the brightness of light that humans can see, whereas PAR describes the brightness of light that plants can use to grow. Specifically, PAR measures the number of photons (that have light wavelengths between 400–700 nm which plants can use to photosynthesize) that hit a 1 square meter surface every second. This type of PAR measurement is called the Photosynthetic Photon Flux Density (PPFD) and is measured in units of μmol/m²/s (which often shortened to “micromols” or just “PAR” amongst aquarists).

A simple way of looking at it is by considering the distance between the light source and the plant itself. When the light is closer to the plant (such as in a shallow aquarium), the PAR will be higher since more light is available to the plant. When the light is further away from the plant (such as in deeper aquarium), there is less light shining on the plant.

Photosynthesis simplified

Why PAR Matters for Aquatic Plants and Planted Tanks

Understanding PAR can be very helpful if you are trying to grow different types of aquarium plants, reduce algae in your aquarium, or compare different types of lighting models to determine which you need for your setup.

Each aquarium plant species has unique needs for lighting and fertilizer, and keeping them under the correct conditions can make a big difference in the health of the plant. In the aquarium market, plants are typically categorized as requiring low, medium, or high light to thrive. This rough guide translates those terms into PAR ranges:

Low lighting: 10–20 PAR
This would be an ideal setup for most low tech plants like anubias and cryptocoryne plants that still thrive even under very little light. Fertilizer will still be required but at minimal levels. High tech equipment like CO₂ (carbon dioxide) injection is not required. Plants will grow slowly but so will algae, making maintenance easier in the long run.

Medium lighting: 20–35 PAR
Most aquarium plants will do well in this range except for highly demanding plants. Fertilizing is essential in order for the plants to thrive since this setup has slightly higher lighting than low tech or low light aquariums. CO₂ is optional but not required. Plants will grow faster, but algae can also pop up faster as well. Regular maintenance and fertilization will be important to ensure the plants thrive and algae doesn’t grow out of control.

High lighting: 40–50+ PAR
Highly demanding plants and carpeting plants do best in high lighting. CO₂ is typically a necessity for such high levels of light, or else algae can take over. A rigid fertilization schedule will also be necessary to match the fast growth rate of the plants. If you wish to grow the most vibrant, red-colored plants, set up a high tech aquarium with strong lighting.

If you have medium to high lighting and still wish to grow low light plants, you might not have to adjust your light. Consider keeping the high light plants closest to the light and in the brightest spots in the aquarium. Plant the low light plants near the substrate or in shaded areas away from direct lighting. This is because low light, slow growing plants tend to accumulate algae on their leaves when constantly exposed to bright light.

When comparing various models of aquarium lights, consider which plants you are trying to grow. Do they require high light or low light to thrive? When in doubt, go for a brighter unit that is also dimmable so that you can easily adjust it for different planted tank builds. Investing in a good light now will likely save you money in the future and ensure you have the capability to grow any plant you want, no matter what its light requirements are.

Aquarium Co-Op Easy Plant LED shining on a planted aquarium

Is PAR Important for a Successful Planted Tank?

PAR and brightness are important factors in the success of a planted tank. Inadequate lighting can cause plants to suffer, and too much light can cause excessive amounts of algae growth. However, it is less important to chase specific PAR values and more important to understand the specific needs of your plants and observe their growth over time to make sure they are healthy. Besides the lighting, other important factors in the success of your planted tank include the fertilizer, substrate, and CO₂ levels. Even so, many aquatic plants are hardy and will adapt to a wide range of conditions. Understanding PAR is just one part of the whole picture of keeping an aquarium.

As a side note, many things can affect the PAR value or amount of photons that travel from your aquarium light and actually reach the aquarium plants. For example:

Aquarium lids (e.g., greenhouse panels allow more light through than glass)
Ripples in the water from surface agitation
Depth of the fish tank
Different colored backgrounds
Light or dark substrates
Tannins in the water
Shadows from plants and decor
Floating plants or tall plants (like vallisneria) at the surface

Measuring PAR on the Easy Plant LED

The best way to measure the PAR levels in an aquarium is to use a PAR meter. We set up an experiment to test the PAR output levels from the Aquarium Co-Op Easy Plant LED using a 65-gallon aquarium.

Detailed PAR chart for Easy Plant LED

As you can see, the PAR is the greatest at the center of the tank right underneath the light. The farther down you go in the tank or towards the far corners of the tank, the lower the available PAR becomes. This information can help inform you as to where to put the high light versus low light plants in your aquarium.

Of course, these PAR values were taken when the light was set at 100% brightness. To accommodate any low, medium, or high light plants you wish to grow, the Easy Plant LED has dimmable light settings that allow you to easily adjust the brightness from 10–100%, making it a great, all-purpose light solution that produces excellent plant growth..

Having run hundreds of aquarium lights at the Aquarium Co-Op fish store and on our own personal aquariums, we decided to make our own planted tank light to address all the pain points we’ve seen. The Easy Plant LED is ultra durable, energy efficient, and highly water resistant (in case you accidentally bump it into the tank). Plus, it has an extra-long 12-foot power cord to reach even the most faraway power outlet. For more details, check out the product page with hundreds of reviews written by actual customers.

size, tank mates, reef safe, care

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17 March 2025

There are a lot of different types of wrasse available for the saltwater aquarium. This article will cover the 75 Best types of wrasse, including their scientific name, the maximum size they grow to as adults, in both inches and centimeters, the minimum tank size required to adequately care for them in gallons and liters, their care difficulty, relative aggressiveness, diet, and whether or not they can be kept safely with corals.

75 Best types of wrasse: care guide summary table

The table below lists the 75 best types of wrasse, with a care guide summary. If the table is wider than the screen you are viewing it on, you can scroll left and right on the table itself.

Table 1: 75 Best Types of Wrasse

Type of Wrasse	Scientifc name for type of wrasse	Adult size (in.)	Min. tank size (gal)	Care difficulty	Aggressive	Diet	Reef safe (Yes/No)	Adult size (cm)	Min. tank size (liters)
Adorned Wrasse	Halichoeres cosmetus	5	55	Relatively easy	No	Meaty foods	Yes	13	208
Banana Wrasse	Thalassoma lutescens	12	125	Relatively easy	Yes	Meaty foods	No	30	473
Bird Wrasse	Gomphosus varius	11	125	Relatively easy	Semi-aggressive	Meaty foods	No	28	473
Black Leopard Wrasse	Macropharyngodon negrosensis	4	90	Extremely difficult	No	Meaty foods	Yes	10	341
Blue Flasher Wrasse	Paracheilinus cyaneus	3	55	Relatively easy	No	Meaty foods	Yes	8	208
Blue Throat Fairy Wrasse	Cirrhilabrus cyanogularis	4	90	Relatively easy	No	Meaty foods	Yes	10	341
Bluehead Fairy Wrasse	Cirrhilabrus cyanopleura	5	90	Relatively easy	No	Meaty foods	Yes	13	341
Bluehead Wrasse	Thalassoma bifasciatum	7	70	Relatively easy	Semi-aggressive	Meaty foods	Somewhat	18	265
Bluestreak Cleaner Wrasse	Labroides dimidiatus	5.5	90	Difficult and challenging	No	Meaty foods	Yes	14	341
Blunthead Wrasse	Thalassoma amblycephalum	6	70	Medium difficulty	Semi-aggressive	Meaty foods	Somewhat	15	265
Carpenter’s Flasher Wrasse	Paracheilinus carpenteri	3	55	Relatively easy	No	Meaty foods	Yes	8	208
Chiseltooth Wrasse	Pseudodax moluccanus	10	125	Difficult and challenging	No	Meaty foods	Somewhat	25	473
Darwin’s Glow Fairy Wrasse	Cirrhilabrus sp.	5	90	Relatively easy	No	Meaty foods	Yes	13	341
Dragon Wrasse	Novaculichthys taeniourus	12	180	Medium difficulty	Semi-aggressive	Meaty foods	No	30	681
Dusky Wrasse	Halichoeres annularis	6	70	Difficult and challenging	No	Meaty foods	Yes	15	265
Exquisite Fairy Wrasse	Cirrhilabrus exquisitus	5	90	Relatively easy	No	Meaty foods	Yes	13	341
Filamented Flasher Wrasse	Paracheilinus filamentosus	3.5	55	Relatively easy	No	Meaty foods	Yes	9	208
Fine Spotted Fairy Wrasse	Cirrhilabrus punctatus	5	90	Relatively easy	No	Meaty foods	Yes	13	341
Formosa Wrasse	Coris formosa	24	180	Medium difficulty	Yes	Meaty foods	No	61	681
Goldbar Wrasse	Thalassoma hebraicum	9	125	Medium difficulty	Yes	Meaty foods	Somewhat	23	473
Golden Rhomboidalis Wrasse	Cirrhilabrus rhomboidalis	4.5	90	Relatively easy	No	Meaty foods	Yes	11	341
Green Wrasse	Halichoeres chloropterus	8	70	Medium difficulty	No	Meaty foods	Yes	20	265
Grey Head Wrasse	Halichoeres leucurus	6	70	Medium difficulty	No	Meaty foods	Yes	15	265
Hardwicke Wrasse	Thalassoma hardwicke	8	90	Medium difficulty	Yes	Meaty foods	No	20	341
Harlequin Tusk	Choerodon fasciatus	10	125	Medium difficulty	Semi-aggressive	Meaty foods	Somewhat	25	473
Hooded Fairy Wrasse	Cirrhilabrus bathyphilus	3.5	55	Relatively easy	No	Meaty foods	Yes	9	208
Johnson’s Fairy Wrasse	Cirrhilabrus johnsonii	3	55	Relatively easy	No	Meaty foods	Yes	8	208
Katherine’s Fairy Wrasse	Cirrhilabrus katherinae	4	90	Relatively easy	No	Meaty foods	Yes	10	341
Labout’s Fairy Wrasse	Cirrhilabrus laboutei	5.5	90	Relatively easy	No	Meaty foods	Yes	14	341
Leopard Wrasse	Macropharyngodon meleagris	6	90	Extremely difficult	No	Meaty foods	Yes	15	341
Lineatus Fairy Wrasse	Cirrhilabrus lineatus	5	90	Relatively easy	No	Meaty foods	Yes	13	341
Linespot Flasher Wrasse	Paracheilinus lineopunctatus	3	55	Relatively easy	No	Meaty foods	Yes	8	208
Lunate Fairy Wrasse	Cirrhilabrus lunatus	3.5	55	Relatively easy	No	Meaty foods	Yes	9	208
Lyretail Wrasse	Thalassoma lunare	10	125	Medium difficulty	Yes	Meaty foods	No	25	473
Marble/Hortulanus Wrasse	Halichoeres hortulanus	11	125	Medium difficulty	No	Meaty foods	Yes	28	473
McCosker’s Flasher Wrasse	Paracheilinus mccoskeri	3	55	Relatively easy	No	Meaty foods	Yes	8	208
Melanurus Wrasse	Halichoeres melanurus	4.5	55	Relatively easy	No	Meaty foods	Yes	11	208
Lubbock’s Fairy Wrasse	Cirrhilabrus lubbocki	3.5	55	Relatively easy	Semi-aggressive	Meaty foods	Yes	9	208
Mystery Wrasse	Pseudocheilinus ocellatus	5	90	Relatively easy	Semi-aggressive	Meaty foods	Yes	13	341
Naoko’s Fairy Wrasse	Cirrhilabrus naokoae	4	90	Relatively easy	Semi-aggressive	Meaty foods	Yes	10	341
Nebulous Wrasse	Halichoeres nebulosus	5	90	Medium difficulty	No	Meaty foods	Yes	13	341
Neon Wrasse	Halichoeres garnoti	7	70	Relatively easy	No	Meaty foods	Yes	18	265
Orange-Back Fairy Wrasse	Cirrhilabrus aurantidorsalis	4.5	90	Relatively easy	No	Meaty foods	Yes	11	341
Paddlefin Wrasse	Thalassoma lucasanum	8	70	Medium difficulty	Yes	Meaty foods	Somewhat	20	265
Pearly Wrasse	Halichoeres margaritaceus	5	90	Medium difficulty	No	Meaty foods	Yes	13	341
Pink Margin Fairy Wrasse	Cirrhilabrus rubrimarginatus	5	90	Relatively easy	No	Meaty foods	Yes	13	341
Pink-Streaked Wrasse	Pseudocheilinops ataenia	2.5	15	Relatively easy	No	Meaty foods	Yes	6	57
Pinkface Wrasse	Thalassoma quinquevittatum	7	70	Relatively easy	Yes	Meaty foods	Somewhat	18	265
Radiant Wrasse	Halichoeres iridis	4.5	55	Extremely difficult	No	Meaty foods	Yes	11	208
Red Breast Wrasse	Cheilinus fasciatus	16	180	Medium difficulty	No	Meaty foods	Somewhat	41	681
Red Coris Wrasse	Coris gaimard	15	125	Medium difficulty	Semi-aggressive	Meaty foods	Somewhat	38	473
Red Head Solon Fairy Wrasse	Cirrhilabrus solorensis	5	90	Relatively easy	No	Meaty foods	Yes	13	341
Red Velvet Fairy Wrasse	Cirrhilabrus rubrisquamis	4	90	Relatively easy	No	Meaty foods	Yes	10	341
Red-Fin Fairy Wrasse	Cirrhilabrus adornatus	3	55	Relatively easy	No	Meaty foods	Yes	8	208
Red-Lined Wrasse	Halichoeres biocellatus	4	55	Relatively easy	No	Meaty foods	Yes	10	208
Redfin Wrasse	Cirrhilabrus rubripinnis	4	90	Relatively easy	No	Meaty foods	Yes	10	341
Richmond’s Wrasse	Halichoeres richmondi	7.5	70	Medium difficulty	No	Meaty foods	Yes	19	265
Rose-Band Fairy Wrasse	Cirrhilabrus roseafascia	5.5	70	Relatively easy	No	Meaty foods	Yes	14	265
Royal Flasher Wrasse	Paracheilinus angulatus		55	Relatively easy	No	Meaty foods	Yes	0	208
Ruby Head Fairy Wrasse	Cirrhilabrus cf cyanopleura	5	90	Relatively easy	No	Meaty foods	Yes	13	341
Ruby Longfin Fairy Wrasse	Cirrhilabrus rubeus	3	55	Relatively easy	No	Meaty foods	Yes	8	208
Scarlet Pin Stripe Wrasse	Pseudocheilinus evanidus	3	55	Medium difficulty	Semi-aggressive	Meaty foods	Yes	8	208
Scott’s Fairy Wrasse	Cirrhilabrus scottorum	6	90	Relatively easy	Semi-aggressive	Meaty foods	Yes	15	341
Sea Grass Wrasse	Novaculichthys macrolepidotus	6	70	Medium difficulty	Semi-aggressive	Meaty foods	Somewhat	15	265
Six Line Wrasse	Pseudocheilinus hexataenia	3	55	Relatively easy	Semi-aggressive	Meaty foods	Yes	8	208
Splendid Pintail Fairy Wrasse	Cirrhilabrus isosceles	5	90	Relatively easy	No	Meaty foods	Yes	13	341
Two Spot Wrasse	Cheilinus bimaculatus	6	70	Relatively easy	Semi-aggressive	Meaty foods	No	15	265
Two Tone Wrasse	Halichoeres prosopeion	5	70	Relatively easy	No	Meaty foods	Yes	13	265
Vrolik’s Wrasse, Male	Halichoeres chrysotaenia	5	70	Relatively easy	No	Meaty foods	Yes	13	265
Whip Fin Fairy Wrasse	Cirrhilabrus filamentosus	3.5	55	Relatively easy	No	Meaty foods	Yes	9	208
Yellow Banded Possum Wrasse	Wetmorella nigropinnata	3	15	Relatively easy	No	Meaty foods	Yes	8	57
Yellow Fin Fairy Wrasse	Cirrhilabrus flavidorsalis	3	55	Medium difficulty	No	Meaty foods	Yes	8	208
Yellow Wrasse	Halichoeres chrysus	5	55	Relatively easy	No	Meaty foods	Yes	13	208
Yellowfin Flasher Wrasse	Paracheilinus flavianalis	3.5	55	Relatively easy	No	Meaty foods	Yes	9	208
Yellowtail Wrasse	Anampses meleagrides	9	125	Extremely difficult	No	Meaty foods	Yes	23	473

Care guide summary for 75 types of wrasse, including scientific name, adult fish size (inches & centimeters), minimum tank size (gallons & liters), care difficulty level, reef safe status, diet

Are wrasses hard to keep?

Most wrasses are not hard to keep. They are generally hardy and relatively easy to care for.

Easy to care for types of wrasse for a saltwater tank

Here is a table of relatively easy to care for wrasse types that are not hard to keep:

Table 2: Easy to care for types of wrasse:

Adorned Wrasse	Golden Rhomboidalis Wrasse	Neon Wrasse	Ruby Longfin Fairy Wrasse
Banana Wrasse	Hooded Fairy Wrasse	Orange-Back Fairy Wrasse	Scott’s Fairy Wrasse
Bird Wrasse	Johnson’s Fairy Wrasse	Pink Margin Fairy Wrasse	Six Line Wrasse
Blue Flasher Wrasse	Katherine’s Fairy Wrasse	Pink-Streaked Wrasse	Splendid Pintail Fairy Wrasse
Blue Throat Fairy Wrasse	Labout’s Fairy Wrasse	Pinkface Wrasse	Two Spot Wrasse
Bluehead Fairy Wrasse	Lineatus Fairy Wrasse	Red Head Solon Fairy Wrasse	Two Tone Wrasse
Bluehead Wrasse	Linespot Flasher Wrasse	Red Velvet Fairy Wrasse	Vrolik’s Wrasse, Male
Carpenter’s Flasher Wrasse	Lunate Fairy Wrasse	Red-Fin Fairy Wrasse	Whip Fin Fairy Wrasse
Darwin’s Glow Fairy Wrasse	McCosker’s Flasher Wrasse	Red-Lined Wrasse	Yellow Banded Possum Wrasse
Exquisite Fairy Wrasse	Melanurus Wrasse	Redfin Wrasse	Yellow Wrasse
Filamented Flasher Wrasse	Lubbock’s Fairy Wrasse	Rose-Band Fairy Wrasse	Yellowfin Flasher Wrasse
Fine Spotted Fairy Wrasse	Mystery Wrasse	Royal Flasher Wrasse
Golden Rhomboidalis Wrasse	Naoko’s Fairy Wrasse	Ruby Head Fairy Wrasse

The wrasse types in this table are relatively easy to care for, not hard to keep, like some other species.

Which wrasses are reef safe?

Table 3: Reef safe wrasses for a saltwater tank

Reef safe wrasse types (A-G)	Reef safe wrasse types (H-N)	Reef safe wrasse types (N-R)	Reef safe wrasse types (R-Z)
Adorned Wrasse	Hooded Fairy Wrasse	Neon Wrasse	Ruby Longfin Fairy Wrasse
Black Leopard Wrasse	Johnson’s Fairy Wrasse	Orange-Back Fairy Wrasse	Scarlet Pin Stripe Wrasse
Blue Flasher Wrasse	Katherine’s Fairy Wrasse	Pearly Wrasse	Scott’s Fairy Wrasse
Blue Throat Fairy Wrasse	Labout’s Fairy Wrasse	Pink Margin Fairy Wrasse	Six Line Wrasse
Bluehead Fairy Wrasse	Leopard Wrasse	Pink-Streaked Wrasse	Splendid Pintail Fairy Wrasse
Bluestreak Cleaner Wrasse	Lineatus Fairy Wrasse	Radiant Wrasse	Two Tone Wrasse
Carpenter’s Flasher Wrasse	Linespot Flasher Wrasse	Red Head Solon Fairy Wrasse	Vrolik’s Wrasse, Male
Darwin’s Glow Fairy Wrasse	Lubbock’s Fairy Wrasse	Red Velvet Fairy Wrasse	Whip Fin Fairy Wrasse
Dusky Wrasse	Lunate Fairy Wrasse	Red-Fin Fairy Wrasse	Yellow Banded Possum Wrasse
Exquisite Fairy Wrasse	Marble/Hortulanus Wrasse	Red-Lined Wrasse	Yellow Fin Fairy Wrasse
Filamented Flasher Wrasse	McCosker’s Flasher Wrasse	Redfin Wrasse	Yellow Wrasse
Fine Spotted Fairy Wrasse	Melanurus Wrasse	Richmond’s Wrasse	Yellowfin Flasher Wrasse
Golden Rhomboidalis Wrasse	Mystery Wrasse	Rose-Band Fairy Wrasse	Yellowtail Wrasse
Green Wrasse	Naoko’s Fairy Wrasse	Royal Flasher Wrasse
Grey Head Wrasse	Nebulous Wrasse	Ruby Head Fairy Wrasse

Wrasses that are traditionally considered to be reef-safe, listed in alphabetical order by common name

17 Types of wrasse that are not reef safe or are somewhat reef-safe with caution advised

Table 4: 17 Types of wrasse that may not be reef safe

Type of wrasse	Scientific name	Min. tank size (gallons)	Reef safe	Aggressive	Care difficulty
Bluehead Wrasse	Thalassoma bifasciatum	70	Somewhat, caution advised	Semi-aggressive	Relatively easy
Blunthead Wrasse	Thalassoma amblycephalum	70	Somewhat, caution advised	Semi-aggressive	Medium difficulty
Chiseltooth Wrasse	Pseudodax moluccanus	125	Somewhat, caution advised	No	Difficult and challenging
Goldbar Wrasse	Thalassoma hebraicum	125	Somewhat, caution advised	Yes	Medium difficulty
Harlequin Tusk	Choerodon fasciatus	125	Somewhat, caution advised	Semi-aggressive	Medium difficulty
Paddlefin Wrasse	Thalassoma lucasanum	70	Somewhat, caution advised	Yes	Medium difficulty
Pinkface Wrasse	Thalassoma quinquevittatum	70	Somewhat, caution advised	Yes	Relatively easy
Red Breast Wrasse	Cheilinus fasciatus	180	Somewhat, caution advised	No	Medium difficulty
Red Coris Wrasse	Coris gaimard	125	Somewhat, caution advised	Semi-aggressive	Medium difficulty
Sea Grass Wrasse	Novaculichthys macrolepidotus	70	Somewhat, caution advised	Semi-aggressive	Medium difficulty

Types of wrasse that are either known not to be reef safe, or where caution is generally advised.

How many gallons does a wrasse need?

Different types of wrasse will require different amounts of water. The minimum number of gallons to keep the smallest types of wrasse is 15 gallons, and the largest wrasse types require 180 gallons of aquarium water or more.

Types of wrasse for a nano aquarium (minimum 15 gallons)

Table 5: 2 Types of wrasse perfect for a nano aquarium

Type of wrasse	Scientific name	Adult size (in.)	Care difficulty level	Reef safe	Aggressive
Pink-Streaked Wrasse	Pseudocheilinops ataenia	2.5	Relatively easy	Yes	No
Yellow Banded Possum Wrasse	Wetmorella nigropinnata	3	Relatively easy	Yes	No

These small types of wrasse on need 15-gallons of water to be happy.

Types of wrasse for a 55-gallon aquarium or larger

Table 6: 24 Best types of wrasse for a 55-gallon aquarium or larger

Type of wrasse	Scientific name	Adult fish size (in.)	Care difficulty	Reef safe	Aggressive
Adorned Wrasse	Halichoeres cosmetus	5	Relatively easy	Yes	No
Blue Flasher Wrasse	Paracheilinus cyaneus	3	Relatively easy	Yes	No
Carpenter’s Flasher Wrasse	Paracheilinus carpenteri	3	Relatively easy	Yes	No
Filamented Flasher Wrasse	Paracheilinus filamentosus	3.5	Relatively easy	Yes	No
Hooded Fairy Wrasse	Cirrhilabrus bathyphilus	3.5	Relatively easy	Yes	No
Johnson’s Fairy Wrasse	Cirrhilabrus johnsonii	3	Relatively easy	Yes	No
Linespot Flasher Wrasse	Paracheilinus lineopunctatus	3	Relatively easy	Yes	No
Lunate Fairy Wrasse	Cirrhilabrus lunatus	3.5	Relatively easy	Yes	No
McCosker’s Flasher Wrasse	Paracheilinus mccoskeri	3	Relatively easy	Yes	No
Melanurus Wrasse	Halichoeres melanurus	4.5	Relatively easy	Yes	No
Lubbock’s Fairy Wrasse	Cirrhilabrus lubbocki	3.5	Relatively easy	Yes	Semi-aggressive
Pink-Streaked Wrasse	Pseudocheilinops ataenia	2.5	Relatively easy	Yes	No
Radiant Wrasse	Halichoeres iridis	4.5	Extremely difficult	Yes	No
Red-Fin Fairy Wrasse	Cirrhilabrus adornatus	3	Relatively easy	Yes	No
Red-Lined Wrasse	Halichoeres biocellatus	4	Relatively easy	Yes	No
Royal Flasher Wrasse	Paracheilinus angulatus		Relatively easy	Yes	No
Ruby Longfin Fairy Wrasse	Cirrhilabrus rubeus	3	Relatively easy	Yes	No
Scarlet Pin Stripe Wrasse	Pseudocheilinus evanidus	3	Medium difficulty	Yes	Semi-aggressive
Six Line Wrasse	Pseudocheilinus hexataenia	3	Relatively easy	Yes	Semi-aggressive
Whip Fin Fairy Wrasse	Cirrhilabrus filamentosus	3.5	Relatively easy	Yes	No
Yellow Banded Possum Wrasse	Wetmorella nigropinnata	3	Relatively easy	Yes	No
Yellow Fin Fairy Wrasse	Cirrhilabrus flavidorsalis	3	Medium difficulty	Yes	No
Yellow Wrasse	Halichoeres chrysus	5	Relatively easy	Yes	No
Yellowfin Flasher Wrasse	Paracheilinus flavianalis	3.5	Relatively easy	Yes	No

The different types of wrasse listed here would be suitable for a 55-gallon tank or larger.

Do flasher wrasses need sand?

The following genera (plural for genus) need a sand bed to sleep in hide: and Anampses, Halichoeres, Macropharyngodon, and Pseudojuloides. That includes the Yellowtail, Yellow, Green, and Melanurus wrasses.

Wrasse tank mates: best and worst

Compatibility between saltwater fish types is challenging to review, because individual experiences sometimes conflict. The general disposition and typical aggressiveness level of a species is a primary, driving force, but the behaviors of individuals within a species will sometimes be more or less aggressive than the norm.

The relative size of the fish in any aquarium, as well as the order in which they are added to the tank will also play a role in competition for food or territorial aggression.

That is why we need to take the general advice and reports we read online (including this one) with a grain of salt, and whenever possible, use data to inform our decisions.

Best wrasse tank mates

In 2022, Saltwater Aquarium Blog Newsletter Subscribers who had experience with keeping one of the most popular wrasse species, the Six Line Wrasse, were asked to indicate which fish types they were successful in keeping with the wrasse and which species they had personal experience with being incompatible with their wrasse.

I used the tally of compatible and incompatible votes to calculate the percentage of the time the wrasse tank mate was compatible with the wrasse.

Table 7: The best wrasse tank mates, including a compatibility score

Wrasse tank mate type	Compatibility %	Aquarists with success	Aquarists rated incompatible
Clownfish	96%	65	-3
Tangs or Surgeonfish	90%	45	-5
Gobies	91%	43	-4
Angelfish	91%	41	-4
Blennies	88%	38	-5
Cardinalfish	92%	36	-3
Chromis	92%	34	-3
Damselfish	93%	28	-2
Basslets or Grammas	88%	22	-3
Anthias	95%	18	-1
Dottybacks	81%	17	-4
Rabbitfish	93%	13	-1
Butterflyfish	87%	13	-2
Triggerfish	100%	8	0
Dragonets	89%	8	-1

Quantitative data supporting the relatively compatibility of the Six line wrasse with other fish types.

Worst wrasse tank mates

In general, Saltwater Aquarium Blog Newsletter subscribers had more successes than failures keeping Pseudocheilinus hexataenia with other wrasse tank mates. But here are the worst wrasse tank mates that demonstrated the lowest compatibility percentages:

Table 8: The wrasse tank mates with the worst compatibility scores

Wrass tank mates	Compatibility %	Aquarists with success	Aquarists rated incompatible
Other wrasse types	62%	18	-11
Filefish	67%	6	-3
Dartfish	79%	11	-3
Eels	67%	2	-1
Pufferfish	67%	2	-1
Jawfish	75%	3	-1
Lionfish	75%	3	-1

Quantitative data supporting the fish with the lowest compatibility score with the Six-line wrasse.

The most common incompatibility was mixing one type of wrasse with another type of wrasse. Two individual wrasses were successfully kept together only 62% of the time.

While it was not directly specified in the survey (the options were simply to indicate compatibility/incompatibility), dartfish and jawfish are notoriously docile fish. One would expect that the docile fish were likely pestered and harassed by a more aggressive type of wrasse.

Eels and lionfish are predators. I’d exercise caution beyond what it stated here and avoid mixing species, especially given the small sample size of the data here.

Can you have two wrasses in the same tank?

You can have two wrasses in the same tank, but it takes some planning and careful purchasing. Having two wrasses in the same tank was the number one reason for incompatibility between two fish types. Aquarium owners were successful keeping two wrasses together only 62% of the time, in a recent Saltwater Aquarium Blog Survey.

Banana wrasse with clownfish and corals in background

Here are a few guidelines that will help. If you want to keep more than one wrasse in the same tank, don’t plan to keep any of the wrasse types in the Pseudocheilinus or Macropharyngodon genus, as they are notorious for being incompatible with other wrasses. Unfortunately, that rules out the very popular Six-line wrasse, Mystery wrasse, and Leopard wrasse.

Aggression tends to be the worst between males, with more aggression between males of the same species and between males from different types of wrasse. Please keep in mind that, in captivity, it seems that the vast majority (read that as “all”, softened just a bit) of female wrasses turn male eventually, which will likely cause issues later on, so it is generally best to just keep 1 of a given wrasse type.

Which wrasses mix well together?

Here is a presentation from MACNA 2017 that goes deep on these wrasses, including which species can be safely combined in the same saltwater tank:

What to read next

Check out these other great guides:

27 Types of tangs

25 Types of saltwater angelfish

19 Types of clownfish

5 Pufferfish types

References

The Wrasse Guy

Michael, Scott W. Marine Fishes: 500+ Essential-to-Know Aquarium Species. TFH Publications, Inc. 2001.

Can I leave blue light on in a fish tank? Does it hurt fish?

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17 March 2025

A lot of popular LED light models have white and blue lights. Blue light is an important wavelength for photosynthesis (the process where plants turn light into sugar/energy).

Blue light is also frequently used to simulate dawn and dusk light cycles. For example, in an 8-hour photoperiod, an aquarist may choose to run a light with White and Blue LEDs as follows:

12 PM to 2 PM: Blue LEDs only
2 PM to 6 PM: Blue + White LEDs together
6 PM to 8 PM: Blue LEDs only
8 PM until 12:00 PM next day: all LEDs OFF

But the existence of the Blue LEDs, often set up on a different switch setting, as well as the tendency to use those lights in the evening, creates a question I hear fairly commonly.

Can I leave the blue light on in a fish tank?

Blue light in a fish tank should not be left on for more than 12 hours each day. No light in a fish tank should be left on more than 12 hours each day. The fish, invertebrates, and even photosynthetic plants or corals in your tank will be healthiest and grow best with 12-16 hours of darkness each day. If you occassionally forget to turn the blue light off in a fish tank, that is okay, just turn it off next time, or set it on a timer or smart plug, so that you don’t have to remember.

Is blue light bad for my fish?

It seems highly unlikely that normal blue light with typical aquarium use is bad for your fish. There are a few scholarly publications on this and related topics, but the findings across studies seem a bit confounding, at best.

For example, a couple of studies concluded that blue light damages fish eye retinas. This was studied in goldfish and zebrafish (called zebra danios in pet stores near me). They did demonstrate and publish results that showed blue light exposure increased signs of stress and damage to the cells in the retina.

But there are other studies that show blue light actually reduced the stress response in Tilapia, which is a food fish, but is also a Cichlid.

Another study showed that the development of baby guppies was stronger/faster/better in blue light than it was in green or red light.

A different study showed that the species of fish they studied preferentially swam to the areas illuminated with blue or green light, but swam away from yellow and red light.

Why would fish have an instict to swim towards a light that is bad for them.

Here is a table summarizing the studies involving blue light and its effect on fish

Blue light and fish summary conclusion	Study title	Publication	Lead Author
Blue light reduced stress response in tilapia.	Environmental blue light prevents stress in the Nile tilapia	Neurosciences and behavior	Volpato, G.L.
The impact of the color of light on the growth of juvenile fish varied by species. Notably, guppies developed better with blue light. Red light decreased growth in all species.	Influence of Colored Light on Growth rate of Juveniles of Fish	Fish Physiology and Biochemistry	Ruching, A.B.
After 1 week of exposure to blue light from an LED, signs of stress were elevated as well as evidence of damage to retina cells (likely leading to cell death) in goldfish.	Effects of blue light spectra on retinal stress and damage in goldfish	Fish Physiology and Biochemistry	Song, Jin Ah
A species of fish in Tibet swam towards green and blue lights but away from red or yellow, suggesting an affinity/preference for blue and green.	A detailed analysis of the effect of different environmental factors on fish phototactic behavior: directional fish guiding and expelling technique	Behavioral Ecology of Aquatic Animals	Xu, Jiawei
Rearing goldfish under blue light improves their growth rate, immune responses to stress, and behavior	Effect of different monochromatic LED light colors on growth performance, behavior, immune-physiological responses of goldfish Carassius auratus	Aquaculture	Noureldin, Salwa M.

Summary of recent publications about the effects of blue light on fish

Blue light has also been demonstrated to be extremly important to the growth of corals. Most of the facilities that grow corals commercially use a light spectrum combination that is heavily skewed towards the blue light part of the spectrum called AB+ that has been shown to produce the best growth in corals. The top of the line reef aquarium lighting manufacturers, like the Radion XR 15 BLUE lights above my tank, provide templates to automatically use this spectrum and are specifically designed with EXTRA blue LED diodes.

White light becomes more blue the deeper underwater you go

Finally, if you have spent any time snorkeling, or in a deep pool, you noticed that the lower you go, the bluer the light gets. Now, I know not every fish comes from a blue ocean environment, they may spend their time on the surface, where the light would be more white. Also, many freshwater species are in yellow/brown/turbid waters. So perhaps they would be more impacted, but I’m not sure that study has been performed.

One final note–zebrafish are used in studies often as a developmental biology model. My hunch, suspicion, hypothesis is that the studies showing blue light damage to fish eyes were intended more to inform understanding the impact of the blue light from electronics on our eyes than they were intended to show that you shouldn’t leave a blue light on over your fish.

Will plants grow better if I leave the lights on?

Plants and other photosynthetic organisms grow best when they have both light and dark periods. During the light period, plants and photosynthetic organisms like zooxanthellae harness the energy in light to make sugar with carbon dioxide and water. During the dark period, these photosynthetic organisms are like any other organism, where they need to consume those sugars for energy. Blasting too much light, out of balance, disrupts the dark phase and results in less vigor, not more.

That is why it is important to establish a consistent and balanced photoperiod for your tanks, or when trying to grow photosynthetic organisms like phytoplankton. A photoperiod of 8 to 12 hours on and 12 to 16 hours off is typically ideal.

Can I leave blue light on in a fish tank to simulate moonlight?

Fish, coral, and other invertebrate spawnings are often tied to lunar cycles. So the notion of recreating moonlight in your fish tank, instead of just total darkness may encourage more natural cyclical behaviors. But blue lights should not be left on in a fish tank for longer than a few hours, to simulate moonlight.

I am currently running the Corallab AB+ template on Radion XR 15 Blue LED lights, and the program is set for a gentle 3 hour moonlight period, which also creates another interesting viewing opportunity. I enjoy watching the fish and corals start to get ready for the night as the moonlight program gets closer to ending.

Blue lights simulating lunar cycle — This blue light and white light are scheduled to run only 3 hours each night

You could also DIY your own moonlight by having a dim blue light, white light, or combination light mounted above the fish tank. If your LEDs are dimmable, you could set them up to brighten and dim in conjunction with a 28 day cycle to recreate the phases of the moon.

Roxanne, you don’ t have to put on the red light

I just like that song. Didn’t understand it until I got older :). I just counted, and that song repeats “put on the red light” 25 times. Yowza!

Sting, ironically illuminated with a red light. I guess Roxanne did have to turn it on.

References

Noureldin, Salwa M., et al. “Effect of different monochromatic LED light colors on growth performance, behavior, immune-physiological responses of gold fish, Carassius auratus.” Aquaculture 538 (2021): 736532.

Ruchin, A. B. “Influence of colored light on growth rate of juveniles of fish.” Fish physiology and Biochemistry 30.2 (2004): 175-178.

Song, Jin Ah, and Cheol Young Choi. “Effects of blue light spectra on retinal stress and damage in goldfish (Carassius auratus).” Fish physiology and biochemistry 45.1 (2019): 391-400.

Volpato, Gilson Luiz, and R. E. Barreto. “Environmental blue light prevents stress in the fish Nile tilapia.” Brazilian Journal of Medical and Biological Research 34 (2001): 1041-1045.

Xu, Jiawei, et al. “A Detailed Analysis of the Effect of Different Environmental Factors on Fish Phototactic Behavior: Directional Fish Guiding and Expelling Technique.” Animals12.3 (2022): 240

Top 5 Popular Catfish to Enjoy in Your Next Community Aquarium

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17 March 2025

Catfish are an amazing type of aquarium fish because of their special, cat-like whiskers and useful clean-up abilities. However, many catfish are known for having bottomless appetites that will swallow anything that can fit inside their big mouths. If you like community fish tanks as much as we do, you may want to avoid ginormous species like the redtail catfish (Phractocephalus hemioliopterus) or striped Raphael catfish (Platydoras armatulus). Instead, check out these popular (and much smaller) catfish that can be commonly found at pet stores.

1. Cory Catfish

Corydoras splendens (emerald cory catfish)

The quintessential, community-friendly catfish has to be Corydoras catfish. With more than 160 species in this genus, they come in all kinds of patterns and colors, but most of them have armored scales, a wider head, and barbels or whiskers on their face. The usual varieties you can find at pet stores include the bronze cory and albino cory (Corydoras aeneus), panda cory (C. panda), emerald green cory (C. splendens), and peppered cory (C. paleatus).

Cory catfish are well-loved because of their derpy personalities, constant shuffling on the ground while they look for food, and habit of randomly “winking” at you. The corydoras sold in the aquarium hobby stay between 1–3 inches (3–8 cm) and can easily live in a 20-gallon aquarium. Preferred water parameters will depend on the species, but in general, they can live in temperatures of 72–82°F (22–28°C) and pH levels from 6.5–7.8. As a bottom-dwelling schooling fish, get a group of at least six fish of the same species, and feed them lots of different meaty foods, like sinking wafers, frozen bloodworms, and freeze-dried tubifex worms. For more details, see our full care guide and a list of our top 10 favorite corydoras.

2. Otocinclus Catfish

Otocinclus sitting on a plant leaf

While corydoras catfish are excellent at slurping up food scraps and other leftovers in the substrate, otocinclus (or “otos”) are your go-to fish for dealing with algae growth. The 20 or so species in the Otocinclus genus are excellent algae eaters for cleaning up smooth surfaces covered in soft green algae, brown diatoms, and biofilm. They enjoy living in a mature, seasoned aquarium with pH between 6.0–7.5, 70-79°F (21-26°C), and soft to hard GH. Because of their passive temperaments, keep these 1.5- to 2-inch (4–5 cm) catfish with other similar sized tank mates (e.g., chili rasboras, celestial pearl danios, kuhli loaches, and adult cherry shrimp) that won’t outcompete them for food.

Otocinclus sometimes get a bad reputation for being weak, but they are actually quite hardy as long as you (a) pick only the fattest, healthiest otos from the fish store and (b) get them eating as soon as possible. Not all otos like eating the same thing, so try feeding them Repashy Soilent Green, canned green beans, and blanched (or slightly boiled) slices of zucchini. For more info on how to pamper your otocinclus, check out this blog article.

3. Glass Catfish

Kryptopterus vitreolus

The Asian glass catfish or ghost catfish is a 2.5-inch (6.5 cm), midwater schooling fish with an unusual appearance. Its common names come from its clear, slightly iridescent body that allow you to see the skeleton and internal organs. As a shyer oddball fish, make sure to get a group of six or more to bolster their confidence, and house them in a 20-gallon or larger tank with lots of aquarium plants and driftwood to provide hiding spots. They do fine in temperatures of 72–82°F (22–28°C), mildly acidic to neutral water, and moderate hardness. Because they have smaller mouths, feed them little foods like fish flakes, nano pellets, baby brine shrimp, and daphnia. Glass catfish get along with many other community fish, such as tetras, danios, corydoras, and smaller gouramis.

4. Upside-Down Catfish

Synodontis nigriventris

Another unique fish on our list is the upside-down catfish from west Africa. This splotchy, brown-colored fish has the special ability to swim upside-down, allowing it to scavenge for food on the undersides of rocks and branches. It has a bushy face of barbels, a high, rounded back, and a dark-colored belly to help with camouflage while inverted. This 3- to 4-inch (7.5–10 cm) oddball would thrive in a 30-gallon aquarium or bigger with plenty of hardscape and broad plant leaves where they can perch upside-down. They prefer water parameters between 72–82°F (22–28°C), pH from 6–8, and moderate to hard GH. Because of their size, they go well with many peaceful and semi-aggressive animals that are too large to be swallowed, such as Congo tetras and kribensis cichlids. With their ability to feed both from the ground and the water surface, you can feed them almost any fish food, including krill flakes, freeze-dried brine shrimp, pellets, and frozen foods.

5. Pictus Catfish

Pimelodus pictus

If you’re looking to stock a larger tank, consider the lovely pictus catfish. Growing up to 4–6 inches (10–15 cm) in captivity, this species is recognized for its long, trailing whiskers and beautiful, silvery body covered in black spots. Their fin spines can sometimes get caught in fish nets, so it may be better to use a plastic container if you need to transport them to another tank.

This energetic swimmer needs a 4-foot aquarium or longer with dimmer lighting, some hardy, low light plants (e.g. anubias and java fern), and areas to take shelter. They are quite hardy and can thrive in pH levels of 6–8, moderate to hard GH, and 72–78°F (22–26°C). They will happily gorge themselves to the point of obesity, so feed them a wide variety of meaty foods and adjust their portion size until they have a slightly rounded abdomen. Good tank mates include similar-sized, active fish that won’t nibble on their whiskers or get eaten by the catfish — such as medium-sized gouramis, barbs, loaches, and mollies.

Bonus: Plecostomus

Female bristlenose pleco

Plecostomus catfish (also known as plecos or suckermouth catfish) are a group of more than 500 species. They typically have a wide head, armored body, and large suckermouth for grazing on surfaces. However, be careful not to accidentally buy a giant-sized pleco that is best suited for monster tanks. The common pleco (Hypostomus plecostomus) is still often sold at pet stores as a 3-inch (7.6 cm) magical cure for getting rid of algae, but they can grow up to nearly 2 feet long and create large amounts of waste.

Instead, look for the much smaller bristlenose pleco (Ancistrus spp.) and rubber nose pleco (Chaetostoma spp.), which stay between 4–6 inches (10–15 cm). They can be kept in a 20- to 29-gallon fish tank or larger, and most can live in typical tropical temperatures between 74–80°F (23–27°C) and a pH range of 6.5–7.5. As nocturnal fish, they appreciate dimmer lighting and plenty of caves and hides to choose from. These two types of plecos are omnivores and enjoy a well-balanced mix of sinking fish foods such as Repashy gel food, wafers, frozen foods, and canned green beans. Read more about them in our plecostomus article.

We hope you get a chance to try some of these fascinating catfish. While Aquarium Co-Op does not ship live fish, we encourage you to peruse our preferred online retailers to order high-quality fish with excellent shipping.

Damselfish types – Saltwater Aquarium Blog

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17 March 2025

Damselfish are some of the most popular saltwater fish, because they are inexpensive, easy to care for, and hardy. But they can also be aggressive towards other fish in a community tank.

Here are 21 Popular Damselfish Types listed alphabetically by common name:

1. Ambon Damselfish	8. Four Stripe Damselfish	15. Rolland’s Damselfish
2. Azure Damselfish	9. Jewel Damselfish	16. Talbot’s Damselfish
3. Blue Devil Damselfish	10. Lemon Damselfish	17. Ternate Damselfish
4. Blue and Gold Damselfish	11. Neon Damselfish	18. Three Spot Domino Damselfish
5. Bluefin Damselfish	12. Regal Damselfish	19. Three Stripe Damselfish
6. Blue Sapphire Damselfish	13. Pink Smith Damselfish	20. Two Stripe Damselfish
7. Blue Velvet Damselfish	14. Princess Damselfish	21. Yellowtail Damselfish

21 Popular Damselfish Types

Ideal water parameters for Damselfish in a saltwater tank

Most Damselfish types are hardy, easy to care for saltwater fish that do not have very demanding, specific care requirements. The traditional reef aquarium water parameters will be a great fit for them:

Temperature: 73 to 84 Fahrenheit
pH: 8.1 to 8.4
Salinity: 35 ppt (1.025 specific gravity
Ammonia: 0 ppm
Nitrite: 0 ppm

1. Azure Damselfish

Azure Damselfish: one of the most popular damselfish types

The Azure Damselfish is one of the most beloved of the Damselfish Types, because of their bold and beautiful coloration and personalities.

Scientific name	Chrysiptera hemicyanea
Minimum tank size	20-gallons (75.7 L)
Adult fish size	2.75 in. (7 cm)
Aggressiveness	Semi-aggressive
Reef safe	Yes
Care level	Easy

Azure Damselfish

2. Blue Devil Damselfish

Blue devil damselfish is a semi-aggressive damselfish type

The Blue Devil Damselfish is one of the most popular species. As their name suggests, they can be a bit of a devil in your community tank, claiming a large footprint of space in your tank as its own, and “defending it” vigorously.

They are omnivores that will occasionally pick at some algae in the tank, but they should also be fed a varied diet that includes meaty foods and algae-based preparations.

In some varieties, the male’s tail is actually orange.

Scientific name	Chrysiptera cyanea
Minimum tank size	20-gallons (75.7 L)
Adult fish size	2.75 in. (7 cm)
Aggressiveness	Semi-aggressive
Reef safe	Yes
Care level	Easy

Blue Devil Damselfish

3. Yellowtail Damselfish

The Yellowtail damselfish is one of the most popular and least aggressive damselfish types, which still means they are semi-aggressive.

The Yellowtail Damselfish is blessed with the reputation of being one of the least aggressive damselfish, which, along with their gorgeous coloration, hardy constitution and inexpensive price tag, makes them one of the most popular saltwater fish species.

Are yellow tail damselfish reef safe?

Yellow tail Damselfish are reef safe. They will peacefully interact with the corals, clams, and mobile invertebrates in your tank. They are also one of the more peaceful species of damselfish, which makes them less likely to squabble with the other fish in your reef tank, although some individuals will still be territorial.

Scientific name	Chrysiptera parasema
Minimum tank size	20-gallons (75.7 L)
Adult fish size	2.75 in. (7 cm)
Aggressiveness	Semi-aggressive
Reef safe	Yes
Care level	Easy

Yellowtail Damselfish

4. Blue Sapphire (Springer’s) Damselfish

Springer's Damselfish, also known as the Blue Sapphire Damselfish. — Most of the damselfish types can and will change colors slightly depending on their “mood”, time of day/night, or perceived danger. The Blue Sapphire is capable of turning almost completely dark when hiding in the shadows.

Are Springer damsels aggressive?

Spring damsels are listed as “peaceful” on Saltwaterfish.com and Liveaquaria.com, but as is the case with most damselfish species, they will likely be aggressive towards peaceful, timid fish and other damselfish, including clownfish. My recommendation is to consider them semi-aggressive and avoid mixing with peaceful species.

Scientific name	Chrysiptera springeri
Minimum tank size	20-gallons (75.7 L)
Adult fish size	2 in (5.1 cm)
Aggressiveness	Semi-aggressive
Reef safe	Yes
Care level	Easy

Blue Sapphire Damselfish

5. Talbot’s Damselfish

Talbot’s Damselfish is relatively mild-mannered, by damselfish standards, although there are frequent reports of certain individuals being quite territorial, despite their reputation. They come from the Indo-Pacific reefs and need a varied diet to remain healthy, like most Damsels.

Scientific name	Chrysiptera talboti
Minimum tank size	20-gallons (75.7 L)
Adult fish size	2.25 in. (5.7 cm)
Aggressiveness	Semi-aggressive
Reef safe	Yes
Care level	Easy

Talbot’s Damselfish Quick Care Stats

6. Rolland’s Damselfish

Rolland’s Damselfish is an attractive damselfish type with more subdued coloration and markings compared with the other show-offs in the Chrysiptera genus.

Scientific name	Chrysiptera rollandi
Minimum tank size	20-gallons (75.7 L)
Adult fish size	3 in. (7.6 cm)
Aggressiveness	Semi-aggressive
Reef safe	Yes
Care level	Easy

Rolland’s Damselfish

7. Princess Damselfish

The Princess Damselfish is perhaps the most strikingly beautiful of all the damselfish types on this list. Their coloration reminds me of the much coveted Flameback Angelfish. If I was going to risk aggression in my tank to add a Damselfish, it would be to add this beauty to my tank.

Scientific name	Pomacentrus vainly
Minimum tank size	20-gallons (75.7 L)
Adult fish size	2.8 in. (7 cm)
Aggressiveness	Semi-aggressive
Reef safe	Yes
Care level	Easy

Princess Damselfish Stats

8. Blue and Gold Damselfish (Goldbelly)

It is remarkable to me to see that there is a Damselfish type with just about any configuration of blue and gold that you can imagine. The Gold belly, or Blue and Gold Damselfish has a gold belly, as the name implies, that starts with the pectoral fin and extends all the way to the tail.

Scientific name	Pomacentrus coelestis
Minimum tank size	20-gallons (75.7 L)
Adult fish size	3.5 in. (8.9 cm)
Aggressiveness	Semi-aggressive
Reef safe	Yes
Care level	Easy

Blue and Gold (Goldbelly) Damselfish

9. Neon Damselfish (Allen’s Damselfish)

Allen’s Damselfish, which also somehow secured the name Neon Damselfish (they all seem a bit Neon to me), has brilliant blue coloration on the majority of its body, with gold highlights on the ventral, anal and caudal finds, interspersed with blue flecks. They are quite attractive, and also semi-aggressive, just like the rest of the fish on this list.

Scientific name	Pomacentrus alleni
Minimum tank size	20-gallons (75.7 L)
Adult fish size	2.5 in. (6.4 cm)
Aggressiveness	Semi-aggressive
Reef safe	Yes
Care level	Easy

Neon Damselfish Quick Care Stats

10. Lemon Damselfish

If you are interested in having a small, but mighty burst of yellow in your tank, the somewhat overlooked Lemon Damselfish is an attractive damselfish type.

Scientific name	Pomacentrus moluccensis
Minimum tank size	20-gallons (75.7 L)
Adult fish size	2.75 in. (7 cm)
Aggressiveness	Semi-aggressive
Reef safe	Yes
Care level	Easy

Lemon Damselfish Quick Care Stats

11. Ambon Damselfish

Scientific name	Pomacentrus amboinensis
Minimum tank size	20-gallons (75.7 L)
Adult fish size	3.5 in. (8.9 cm)
Aggressiveness	Semi-aggressive
Reef safe	Yes
Care level	Easy

Ambon Damselfish Type Quick Care Stats

12. Pink Smith Damselfish

Jada Pink Smith and Will Smith at the Oscars (pre-slap) GIF in place of an actual picture of the Pink Smith Damselfish as a joke.

Having a little fun with the image above, but the Pink Smith Damselfish (also popularly called Demoiselle) is a relatively subtly colored beauty.

Scientific name	Pomacentrus smithi
Minimum tank size	20-gallons (75.7 L)
Adult fish size	2.75 in. (7 cm)
Aggressiveness	Semi-aggressive
Reef safe	Yes
Care level	Easy

Pink Smith Damselfish Quick Care Stats

13. Regal Damselfish

Scientific name	Neopomacentrus cyanomos
Minimum tank size	20-gallons (75.7 L)
Adult fish size	3 in. (7.6 cm)
Aggressiveness	Semi-aggressive
Reef safe	Yes
Care level	Moderate

Regal Damselfish Quick Care Stats

14. Three stripe Damselfish (Humbug)

The Three Stripe Damselfish has one of the BEST alternate common names–Humbug! They look very similar to the Four Stripe Damselfish, except with no stripe on the tail.

These beautiful fish are often sold as tiny juvenile fish that are commissioned to be the first fish in a new saltwater tank. This causes problems later on, due to their aggressive dispositions.

Scientific name	Dascyllus aruanus
Minimum tank size	20-gallons (75.7 L)
Adult fish size	3.75 in. (9.5 cm)
Aggressiveness	Semi-aggressive
Reef safe	Yes
Care level	Easy

Three Stripe Damselfish

15. Four stripe Damselfish

Four Stripe Damselfish Type of Dascyllus genus — Note the black stripe on the tail fin (caudal fin) distinguishing this Dascyllus from its Three-Striped Cousin

The Four stripe Damselfish is so named because of the three bold stripes on the body of the fish, as well as the fourth stripe of black that covers the tail-end of the caudal fin. Hah! Tail end!. Go ahead, scroll back up, you’ll see. They look almost identical to the Three stripe except for the black tail.

This is a popular and common damselfish type, but they are not always a great choice for the peaceful community tank due to their aggression.

Scientific name	Dascyllus melanurus
Minimum tank size	20-gallons (75.7 L)
Adult fish size	3.25 in. (8.3 cm)
Aggressiveness	Semi-aggressive
Reef safe	Yes
Care level	Easy

Four Stripe Damselfish

16. Two Stripe Damselfish

Scientific name	Dascyllus reticulatus
Minimum tank size	55-gallons (208.2 L)
Adult fish size	3.5 in. (8.9 cm)
Aggressiveness	Aggressive
Reef safe	Yes
Care level	Easy

Three Spot Domino Damselfish

17. Three Spot Domino Damselfish

The Three Spot Domino Damselfish is one of the larger damsels on this list. They should be kept in a tank that is 55-gallons or larger, because they will reach ~5.5 inches as adults. As you can see in the image, they do like to live amongst the tentacles of anemones, just like clownfish.

There is some risk that any/all damselfish will eat invertebrates small enough to swallow. That risk increases with larger species, like the Domino.

Scientific name	Dascyllus trimaculatus
Minimum tank size	55-gallons (208.2 L)
Adult fish size	5.5 in. (14 cm)
Aggressiveness	Semi-aggressive
Reef safe	Yes
Care level	Easy

Three Spot Domino Damselfish

18. Bluefin Damselfish

Topping the charts at a full 7-inch adult length, the substantial Bluefin Damselfish is one of the largest and most aggressive type of damselfish you will encounter at your local fish store. You likely won’t see a full-sized adult, but rather the tiny, cute, seemingly harmless 1.5-2 inch juvenile. But these fish grow up to be quite large in size and are not afraid to throw around their weight.

With that said, they are hardy, reef safe, and easy to care for.

Unnecessary commentary from the author (me): I find it interesting that the common name for Neoglyphidodon melas is the Bluefin Damselfish. They clearly do have blue highlights to their ventral fins, which is a distinguishing feature, but I’m not sure it captures the essence of the fish.

Scientific name	Neoglyphidodon melas
Minimum tank size	55-gallons (208.2 L)
Adult fish size	7 in. (17.8 cm)
Aggressiveness	Semi-aggressive
Reef safe	Yes
Care level	Easy

Bluefin Damselfish Stats

19. Ternate Damselfish

Scientific name	Amblyglyphidodon ternatensis
Minimum tank size	20-gallons (75.7 L)
Adult fish size	3 in. (7.6 cm)
Aggressiveness	Semi-aggressive
Reef safe	Yes
Care level	Easy

Ternate Damselfish

20. Blue Velvet Damselfish

The Blue Velvet Damselfish is a commonly stocked and attractive fish as a juvenile that grows to be very large (6 inches/15 cm) as an adult. They are also one of the less fortunate fish, that like me, becomes less attractive as an adult than as a juvenile :).

The blue neon/velvet stripes fade to become a predominantly drab/dark colored and aggressively dispositioned large fish.

Buyer beware.

Scientific name	Paraglyphidodon oxyodon
Minimum tank size	20-gallons (75.7 L)
Adult fish size	6 in. (15.2 cm)
Aggressiveness	Semi-aggressive
Reef safe	Yes
Care level	Easy

Blue Velvet Quick Care Stats

21. Jewel Damselfish

Hard to believe we can come to the bottom of the list of popular damselfish types and just be getting to the Jewel Damselfish, but that is a testament to how diverse and attractive these beauties are. The Jewel is another one of the larger fish on this list, growing to about 6 inches/15 cm in total length as adults.

They are reef safe towards corals, but may be a problem if you stock small invertebrates, as they are opportunistic hunters.

Scientific name	Microspathodon chrysurus
Minimum tank size	55-gallons (208.2 L)
Adult fish size	6 in. (15.2 cm)
Aggressiveness	Semi-aggressive
Reef safe	Yes
Care level	Easy

Jewel Damselfish

Which is the most peaceful damselfish type?

Based on reputation and personal experience, the most peaceful damselfish types are likely Springer’s, Yellowtail, and the Azure damselfish, which also makes them the least aggressive. However, there is no definitive or authoritative way to rank the aggressiveness of different fish species.

You may notice that these are all members of the Chrysiptera genus, a group of relatively smaller and directionally more peaceful type of damselfish.

There is an ancient Saltwater Aquarium Blog proverb passed down from my elders that states:

“The most peaceful damselfish is the one that is not in your tank.”

Ancient Saltwater Aquarium Blog Proverb etched into a stone tablet found in my deep sand bed

What are the most aggressive damselfish types?

The most aggressive damselfish types are the Blue Devil, Two stripe, Three stripe, Three spot, Four stripe, Bluefin, Velvet, and Jewel Damselfish.

The Blue Devil Damselfish is one of the most aggressive, especially for its size.

If you’re thinking…that’s a lot of species…you are right. Damselfish can be quite aggressive.

Interestingly enough, Saltwater Aquarium Blog elders also passed down a proverb about this:

“The most aggressive damselfish is the one that is in your tank.”

Ancient Saltwater Aquarium Blog Proverb etched into a stone tablet found in my deep sand bed

Three spot Domino Damselfish Type in Anemone

Can you mix different damselfish?

Most damselfish are aggressive or semi-aggressive saltwater fish. Mixing different damselfish, or even two or more of the same type of damselfish can be tricky, but it is possible. To do so, here are 5 tips to help:

Add them to the quarantine tank and display tank at the same time
Combine similarly-sized individuals (both current size and anticipated adult size)
Choose similarly aggressive species
Add 3 or more from each species
Add cleaner fish and shrimp to the tank

1. Add damselfish to the tank at the same time to disperse aggression

Damselfish aggression is generally thought to be in response to a natural tendency to protect and defend their territory from interlopers. If you add the damsels at different times, the incumbent fish will have already established a territory and will therefore be more aggressive in protecting it.

When the fish are all introduced at the same time, they establish a hierarchy and divide up the available space. Assuming there is enough room for everyone, the end result should be a more balanced distribution of territory.

2. Choose similarly sized fish to avoid bullying

The smallest Damselfish species grow only to about 2 inches (5 cm) in le.ngth as fully grown adults, while others grow to 6 or 7 inches (15.2 or 17.8 cm)!

Damselfish can sometimes be tank bullies. Just like all bullies, their first option is to pick on someone they perceive as weaker than themselves. One of the quickest ways to create that imbalance is to mix damselfish species that are different sizes today.

You will also want to be careful not to mix damselfish species that will be dramatically different sizes in a few months. Even though they may all be cute ~1.5 inch juveniles in the tank at your local fish store, mixing a 7-inch Bluefin Damselfish with a ~2-3 inch Azure Damselfish will result in a David vs. Goliath situation before long.

3. Choose similarly aggressive species to strive for balanced aggression

Attempting to manage aggression in an aquarium is a bit like fighting fire with fire. Your goal is to achieve balance. So if you want to mix damselfish species, you will likely have the greatest success if you try to mix damsels with similar aggressive dispositions. Don’t mix semi-aggressive varieties with semi-peaceful.

Four stripe damselfish in birds nest coral

4. Choose larger, odd numbers of fish to strive for dispersion of aggression

One interesting aspect of aggression exerted by aggressive fish species is that it tends to be relatively constant. As long as the aggressor has energy, feels safe, and can see the threat, they will likely attack and defend.

So one of the strategies to help manage aggression in fish is to have many, similarly aggressive fish all together. When that occurs, there is less ‘picking’ on a weaker individual, and instead, the aggression is spread out on several other targets. Since we also carefully selected those “targets” to also be similarly aggressive, they, too, have their own targets, and so on.

In that way, you create a web of dispersed aggression, which helps prevent any one or two fish from becoming targeted so much that they become sick, injured, or worse.

5. Add cleaner fish and shrimp to the tank

There was a scientific study many years ago demonstrating that cleaner fish reduce aggression in a saltwater aquarium. Essentially, the more the fish in the study got cleaned by the cleaner wrasse, the less aggression they displayed–not just because of the ‘time outs’ but it somehow soothed the savage underwater beasts.

I can’t say for sure whether or not that specific insight could be successfully applied to this situation, but cleaner fish and shrimp are awesome…so why not give it a try?

Do damsels get ich?

Ich, “ick” or “white spot disease,” is caused by a parasite that attacks the gills and skin of saltwater aquarium fish, including damsels and damselfish.

Why is my damsel turning white?

If you see your damsel turning white at night, looking more pale than during the day, this is a normal, routine event, as part of preparation for rest. If your damsel is turning white during the day, it could be a symptom of stress, illness, or malnourishment.

If your damsel is turning white, you should try to remove the cause of the stress and see if you can improve the nutritional quality of the food.

Can damselfish live with clownfish?

Damselfish and clownfish are likely to be aggressive towards each other and should not live together in the same saltwater tank, unless you have a very large aquarium.

Are damselfish hardy?

Damselfish are some of the most hardy saltwater fish available for a marine aquarium. They are tolerant of less-than-perfect water parameters, eager to eat the majority of available foods and most live a long time. Damselfish are often one of the first fish added to a new saltwater tank because they are so hardy.

Caution is advised though, because most damselfish species can be moderately aggressive, which can cause problems when you try to add your second, third and subsequent fish. So although their constitution is hardy, making them an ideal starter fish, their aggressive behavior is not.

Can damselfish change color?

Damselfish can change color and will change color to a lighter/paler shade at night and to a darker shade when stressed or scared. Springer’s damselfish will turn from blue to almost black when stressed and trying to avoid a predator.

Are damselfish jumpers?

All saltwater fish are somewhat susceptible to jumping out of an aquarium with no lid if they feel sufficiently startled but damselfish a moderate risk of being a “jumper,” similar to that of a clownfish. Dartfish, wrasses, and jawfish are notorious jumpers.

References

Michael, Scott W. Marine Fishes: 500+ Essential-to-Know Aquarium Species. TFH Publications, Inc. Neptune City, NJ 2001

Live Aquaria

When Should I Dose Potassium Fertilizer in My Planted Aquarium?

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17 March 2025

Just as your fish need to have a healthy diet and clean water to grow big and beautiful, plants also require a special “diet” of lighting and nutrients to thrive. To have the proper building blocks needed to grow well, they need large amounts of macronutrients (like nitrogen, potassium, and phosphorus) and trace amounts of micronutrients (like magnesium and zinc). Our Easy Green all-in-one liquid fertilizer contains all the correct ratios of these macronutrients and micronutrients that can be easily dosed with a simple pump head or dropper cap. It comes with a very strong 9.21% concentration of potassium (also known as soluble potash or K₂O), so when is it necessary to dose even more potassium in your planted tank?

Do My Aquarium Plants Need More Potassium?

Potassium is responsible for all sorts of vital functions in live plants, both terrestrial and aquatic species. It regulates water and nutrient movement between plant cells, is used in photosynthesis and protein synthesis, activates dozens of enzymes, and controls the stomata (or pores on the leaf’s surface that open and close to allow gas and water exchange). Potassium also transports sugars, starches, and other organic compounds so they can be stored inside bulbs, tubers, and fruits.

Do my aquarium plants have a potassium deficiency? Most of the time when a plant is lacking macronutrients (like potassium), any remaining macronutrients within the plant are moved from the older leaves to the newest shoots to save them. It is very easy to see when you have a potassium deficiency because the older, existing leaves develop very distinctive pinholes that are sometimes rimmed with brown or yellow. If the potassium deficiency continues, then the pinholes will grow into bigger and bigger holes until the entire leaf decays away. For more details on plant nutrient deficiencies, see our full article.

Plants that lack potassium develop small pinholes on the older leaves.

In the majority of planted tank, Easy Green fertilizer provides plenty of potassium and other nutrients, so you won’t need to add any supplemental fertilizers. However, if you are growing high light plants in a high tech aquarium with carbon dioxide (CO₂) injection, they can grow incredibly quickly and may be absorbing potassium at a much faster rate than other nutrients. Also, some plants like java fern and anubias thrive in environments with more potassium. Therefore, if your tank has greater potassium demands than usual, keep reading.

Some plants like java fern and anubias can consume greater amounts of potassium and may develop yellowing and browning if they lack the proper nutrients.

How Often Should I add Potassium to My Aquarium?

Easy Potassium is our potassium supplement that contains a 9.12% concentration of soluble potash (K₂O) derived from potassium sulfate and potassium citrate. Like all the products in our Easy Fertilizer line, it is completely safe for fish, shrimp, snails, and other aquatic animals. Plus, it comes in two sizes with easy-to-use dispensers for quick dosing.

The 500 ml (16.9 oz) bottle treats 5,000 gallons total and has a pump head on top. Dose 1 pump (1 ml) per 10 gallons of water to add 2 ppm of potassium.
The 120 ml (4 oz) bottle treats 1,200 gallons total and has a dropper cap on top. Dose 2 drops per 1 gallon of water to add 2 ppm of potassium.

If you aren’t sure how much potassium your planted tank needs, start off slowly and only dose once a week. Wait two weeks to see the effect it has on your plants, and consider increasing the dosage to two to three times a week if needed. Several planted aquarium articles recommend aiming for approximately 5–20 ppm potassium in your water, depending on the needs of the plants. In general, an excess of potassium in planted tanks does not cause algae growth, and experienced aquatic horticulturists have dosed up to 100 ppm potassium in high tech planted aquariums without experiencing any toxicity issues.

Easy Potassium

Why doesn’t Easy Green contain more potassium? As mentioned before, Easy Green already contains very high amounts of potassium. In fact, our formula has already reached the saturation point for potassium, so the only way to add more is to create a separate potassium supplement. For most aquariums, the amount of potassium in Easy Green is plenty sufficient, but if you have a unique case of using a high tech aquarium or owning lots of potassium-hungry plants, make sure to give Easy Potassium a try.

A list of Stunning Nano Fish

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17 March 2025

Are you looking for the perfect small fish to add to your nano aquarium? Whether you have a 10-gallon tank or something even smaller, there are plenty of vibrant, fascinating fish species that will thrive in your setup. After years of experience in fishkeeping and working in the aquarium industry, I’ve compiled a list of my all-time favorite small fish. These species are hardy, beautiful, and well-suited for small tanks.

1. Pygmy Corydoras – The Tiny Bottom Dwellers

Pygmy Corydoras are an excellent choice for small aquariums. These tiny catfish are social, active, and great for keeping the bottom of your tank clean. They’re hardy and adaptable to different water parameters, making them easy to care for. Plus, they are affordable and thrive in groups of six or more. They tolerate a wide variety of temps from 70 to 80 degrees, pH from 6.5 to 8.0, and soft to hard water. Grab yourself a group of 6 or more and enjoy these guys on the bottom of your tank.

2. Clown Killifish – The Rocket-Like Swimmers

Clown Killifish are colorful, top-dwelling fish that resemble miniature rockets. Males boast stunning colors, while females are more muted. They are jumpers, so a well-fitting lid is essential. These fish are relatively easy to breed and enjoy feeding on small floating foods such as baby brine shrimp and frozen Cyclops. They tolerate a wide temperature range from 68 to 80 degrees. They can live in water with a pH from 6.5 to 8.2, and almost any hardness. When breeding, aim for the middle of all of those ranges.

3. Celestial Pearl Danio (Galaxy Rasbora) – A Timeless Classic

Celestial Pearl Danios are one of the most stunning small fish available. With their intricate patterns and striking colors, they bring elegance to any aquarium. They thrive in cool water conditions and are relatively easy to breed. Their mid-water swimming habits make them ideal for a diverse nano tank. They can live in temperatures from 68 to 78, with pH being 6.5 to 8.0 . Hardness can be soft to hard water. For spawning, target the middle and keep them in groups of 6 or more.

4. White Cloud Mountain Minnows – The Hardy Beauties

White Clouds are often overlooked, but they are among the best small fish in the hobby. Available in normal, gold, and long-finned varieties, these fish can even survive in outdoor ponds with freezing temperatures. They are extremely hardy and adapt well to various water conditions. They can handle a temperature range of 30 to 90 degrees, any pH above 6.5, and any hardness. You will only need a pair to spawn them if kept alone. These fish are easy to breed and will usually spawn and make you more.

5. Chili Rasbora – Tiny Fish with Fiery Colors

Chili Rasboras are known for their intense red coloration, which becomes more vibrant in well-maintained tanks. They prefer mid-water areas and do well in heavily planted setups. While they are easy to keep, breeding them is quite challenging. If you manage to breed them successfully, consider sharing your method with the aquarium community! They prefer temperatures from 72 to 82. pH can range from 6.5 to 8.0. Water hardness can be from soft to moderately hard. Keep in groups of 6 or more.

6. Neon Green Tetra – A Unique Twist on a Classic

Neon Green Tetras are even smaller than traditional Neons and display a mesmerizing green hue when viewed from above. They prefer warmer waters and are best suited for aquarists looking to add a unique pop of color to their nano tank. Temperatures can range from 74 to 82, pH from 6.5 to 7.8, with soft to moderate hardness. Keep in groups of 6 or more. Best viewed from standing above to maximize the green color.

7. Fancy Guppies & Endlers – A Rainbow of Options

Guppies and their smaller relatives, Endlers, are excellent choices for small tanks. They come in a vast array of colors and patterns and are incredibly easy to breed. With proper care, they will thrive in hard water and higher pH environments, making them one of the most versatile nano fish. Temperatures can range from 72 to 82 with a pH above 7.0 up to 8.5. Moderately hard to very hard water with lots of minerals is ideal. A single pair can make lots of fry. Keep in groups with more females than males.

8. Sparkling Gourami – The Subtle Stunner

Sparkling Gouramis have an iridescent glow when light hits them just right. These fish exhibit fascinating behavior, often stalking their food like tiny predators. They help control small pest populations like Hydra and add a unique dynamic to a nano tank. Temperatures can range from 72 to 80 degrees, with a pH level of 6.5 to 7.8 with low to moderate hardness. These are micro predators that can even hunt some hydra for you.

9. Kuhli Loach – The Playful “Danger Noodle”

Kuhli Loaches are bottom-dwelling, eel-like fish that come in various colors and patterns. They are social and should be kept in groups. While they spend much of their time hiding, they are a joy to watch when they emerge and explore their environment. Temperatures should range between 72 to 82, with a ph above 6.5 to 8.2. Soft to hard water. Keep in groups of 3 or more.

10. Apistogramma (Dwarf Cichlids) – Small But Mighty

If you’re looking for a more interactive and rewarding fish, a pair of Apistogramma is an excellent choice. These dwarf cichlids require specific water conditions, including soft, warm water, but they will reward you with fascinating behavior and potential breeding opportunities. Temperatures should be 82 to 85 for best results, with a pH of 6.5 to 8.0 with soft to moderate water hardness. A single pair when happy can produce lots of fry. Watch out for sneaker males, which means when buying a boy and a girl, the sexually immature male can look like a female and act like one with a dominant male in a tank.

11. Shell-Dwelling Cichlids (Neolamprologus Multifasciatus) – The Burrowing Engineers

Multis, or shell dwellers, are tiny African cichlids that live in and around shells. They constantly dig and rearrange their environment, making them endlessly entertaining to watch. They prefer high-pH, hard water and do best in species-only setups. Temperatures can range from 72 to 82 with a pH of 7.0 to 8.5. Moderate to hard water is ideal Buying a group of 6 usually gets you at least one female. With enough shells and lots of small foods floating into the shells, you’ll make fry. I recommend feeding both our magic small fish feed to feed the fry and the community pellets for the adults.

12. Red Neon Rainbowfish – A Burst of Color

Red Neon Rainbowfish are small, bright, and active. While they can be pricey, they are well worth the investment for their beauty and engaging behavior. They prefer warm water and do well in groups, where males will display their best colors. Temperatures can range from 70 to 82 degrees with a pH of 7.0 to 8.0 with soft to moderately hard water. A single pair can give you eggs with a floating spawning mop. Raising the fry requires very tiny powder foods with a long small fry grow out time.

Final Thoughts

There are countless small fish species that make excellent additions to nano aquariums. Whether you prefer the elegance of Celestial Pearl Danios, the hardiness of White Clouds, or the playful nature of Kuhli Loaches, there’s a perfect small fish for every aquarist.

5 Easy Tricks to Supercharge Your Aquarium Filter

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9 February 2025

Countless aquarium filtration hacks exist, promising improved efficiency, cost savings, and more. While some are merely fads, others are genuine gems discovered by seasoned fishkeepers. Having used hundreds of filters in our store and personal fish rooms, we’ve compiled the top 5 simple yet effective tips for maximizing your filter’s performance.

Reusable Filter Media

Ever wondered how long those filter cartridges included with aquarium kits (HOB or internal filters) actually last? Sadly, many manufacturers use disposable cartridges, recommending replacement every 1-3 months, primarily for profit. These cartridges, typically containing filter floss for mechanical filtration and activated carbon for chemical filtration, quickly become clogged and lose effectiveness. Their design also makes them difficult to clean and reuse.

The good news is that you can easily replace these disposables with reusable media like coarse sponge pads and bio-rings. Simply clean them in a bucket of old tank water (no soap!) when dirty and return them to the filter. This not only saves money but also preserves the crucial beneficial bacteria that provide biological filtration, consuming waste and purifying the water. These reusable options often last for years and can even be used to cycle new tanks. Consider reusable chemical filtration media like Seachem Purigen, which, unlike activated carbon, can be regenerated with a bleach solution.

What is Pre FIlter Sponge

For any filter with an intake tube (HOB, canister, etc.), a pre-filter sponge is invaluable. This simple, cylinder-shaped sponge slips over the intake tube like a sock, preventing fish food, debris, small creatures, and substrate from entering and potentially damaging the filter motor. Acting as the first stage of mechanical filtration, it traps the majority of the larger particles before they reach the main filter media. This keeps the media cleaner, leading to more efficient filter operation and less frequent cleanings. The pre-filter sponge also provides additional surface area for beneficial bacteria, boosting biological filtration. While a fine sponge might seem like it would trap more particles, we recommend a coarse sponge with larger pores. Fine sponges can clog easily, putting strain on the filter and shortening its lifespan. For more detailed information on choosing and fitting the perfect pre-filter sponge, check out our full article.

Keep an Air Stone in your Filter

Sponge filters typically produce large, irregular bubbles, creating a stop-and-go flow. Adding an air stone inside the sponge filter transforms these large bubbles into a consistent stream of tiny bubbles. This creates a more even water flow through the sponge, improving its particle-trapping efficiency and reducing noise. For instructions on installing an air stone in a sponge filter, see [link to instructions].

Even if you don’t use sponge filters, an air stone can benefit your hang-on-back filter. Placing one in the HOB filter’s media compartment significantly boosts the growth of beneficial bacteria and increases oxygen levels in the water, creating a healthier environment for your fish and plants.

Add Carbon to a Sponge Filter

Adding carbon to a sponge filter, while not the most conventional method, can be a useful technique when dealing with specific water quality issues. Since sponge filters lack a dedicated media compartment, the key is to utilize carbon-infused media pads. These pads, typically designed for other filter types, can be adapted to work effectively with sponge filters. The process involves cutting the pad to an appropriate size and securely wrapping it around the sponge filter itself, typically using a rubber band to hold it in place. This placement ensures that water drawn through the sponge filter also passes through the carbon pad.

The mechanics of this setup are quite simple. As the air bubbles rise through the sponge filter’s lift tube, they create an upward current, drawing water into and through the filter. By positioning the carbon pad around the sponge, the incoming water is forced to flow through the pad before reaching the sponge material. This process effectively removes toxins and impurities from the water as it filters through the carbon. The constant flow of water ensures continuous contact with the carbon, maximizing its absorption capabilities.

This method isn’t limited to just carbon pads. Other chemical filtration pads, such as those designed for ammonia or phosphate removal, can be used in the same manner. This adaptability makes the technique particularly valuable when dealing with specific water parameters that need to be addressed without altering the established biological filtration within the sponge filter itself. It offers a simple and effective way to incorporate chemical filtration into a sponge filter system, even without a traditional media compartment.

Keeping More Filtration is not good

The common belief that “more filtration is always better” can be misleading, particularly in the aquarium hobby. While adequate filtration is crucial for maintaining water quality, simply adding more filters isn’t a guaranteed path to success. In fact, it can sometimes create more problems than it solves. Each additional filter introduces another potential point of failure, increasing the risk of overflows, leaks, and other malfunctions. Furthermore, maintaining multiple filters requires more time, effort, and expense, from cleaning filter media and impellers to replacing parts. This increased complexity can ironically make it easier to overlook a developing problem with one of the many systems, potentially leading to a decline in water quality.

A more effective approach is to focus on optimizing the filtration you already have. This involves ensuring your existing filter is appropriately sized for your aquarium, performing regular maintenance, and implementing techniques to maximize its efficiency. As discussed previously, using a pre-filter sponge, switching to reusable media, and even incorporating an air stone can significantly enhance a single filter’s performance. By streamlining your filtration setup and focusing on a single, well-maintained filter, you can often achieve better results with less effort and fewer potential headaches. This “less is more” philosophy not only simplifies maintenance but also encourages a more attentive approach to your aquarium’s health, as you’re more likely to notice any changes in its operation.

A Beginner’s Guide to Marine Aquariums

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8 February 2025