What Fish Eat Algae: The Complete Guide | Aquascape Addiction

What Fish Eat Algae: The Complete Guide

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When it comes to the question of “what fish eat algae?” the response is vast because there are so many different types of fish and aquatic animals that will consume various types of algae, the kind you get really depends on your tank and your needs.

What Fish Eat Algae: The Complete Guide

We are here today to discuss what the best type of algae eating fish is, what other types of fish and aquatic animals eat algae, as well as what kinds of algae you may find in your fish tank.

Types Of Algae Found In Aquariums

There are various different types of algae which you may find growing in your fish tank. You may think that the type of algae is irrelevant, but when it comes to getting the right fish for eating and getting rid of the algae it is quite important to know the differences. Not all fish will eat all types of algae, so depending on what kind of algae you have you will want to get different algae eating fish.

Let’s quickly go over the different kinds of algae that could be in your fish tank.

  • Green Water – This is the first kind of algae you may find and it is actually the rarest of them all, not to mention that it’s the worst too, which is why we’re getting it out of the way. Algae eating fish won’t eat this stuff and it’s very hard to get rid of, often warranting a complete overhaul of your fish tank and the changing of water.

  • Gold Slime – This stuff looks like slime and can appear in dots on the glass of your aquarium as well as on the fixtures. This algae is quite common and most often appears in aquariums that have a low light level or are new. This type of algae is readily eaten by fish and is also fairly easy to wipe away.

  • Green Slime – This is perhaps the most common type of aquarium algae, but it’s also the kind that is seen the least by enthusiasts because it is eaten by almost all fish.

  • Thread Algae – There are various types of hair or thread algae and they all take on the appearance of thin strands that wave about in the current.

  • Brush Algae – This kind of algae most often appears on plants, especially those with rough edges and it has the appearance of thick tufts of hair. This stuff is hard to wipe away and therefore it’s useful to have some algae eating fish.

  • Green Dot Algae – This is a very common type of algae that forms in green dots along the glass of your aquarium as well as the fixtures. It isn’t too bad when there is only a little of it, but it can quickly multiply to create a thick layer on the glass. Unfortunately most fish will not eat this algae, and the ones that do won’t have a big effect on it.

  • Blue/Green Algae – This is also a common type of algae found in fish tanks and is of course blue or green in color. It doesn’t attach well to the surfaces in the aquarium and tends to float around. The real problem with this type of algae is that it is not edible for most kinds of fish due to its toxicity.

  • Red Algae: is covered separately here.

What Is The Best Algae Eating Fish?

There are several different animals and fish that you can get for your fish tank for the purposes of getting rid of algae. As well there are different snails(like the Zebra Nerite Snail) and other creatures that will eat algae all day long too. In our opinion the very best algae eating fish out there is the Twig Catfish.

The Twig Catfish is most likely the best algae eating fish out there, mainly because it has a ravenous appetite and ill consume virtually any type of algae that may appear in your fish tank. This fish is so hungry that if you don’t have enough algae in your fish tank you will have to supplement its diet with algae tablets; that’s how good this fish is!

Something that needs to be noted is that the Twig Catfish does quite well with other peaceful fish such as Rashoras, Pencil Fish, Hatchets, and Tetra Fish. On the other hand they don’t do so well with more aggressive fish such as Barbs and Cichlids.

These fish also don’t do well when there are big changes in the consistency of the water so be careful to keep the water at the same parameters when housing the Twig Catfish. As a base line, the Twig Catfish should be in a tank that is at least 70 liters in size. The question of “what fish eat algae?”, especially the number one choice, is best answered by saying that the Twig Catfish is your number one option.

Other Algae Eating Fish

Twig Catfish aren’t the only kind of fish or animal out there that likes to eat algae and is useful for your aquarium. There are many other kinds of fish and aquatic animals that will help rid your aquarium of bad algae. Here are some of the best ones for any aquarium.

The Siamese Algae Eater

These fish are great for eating algae and cleaning out your fish tank because they tend to eat types of algae that other fish don’t like, mainly brush algae and thread algae. Siamese Algae Eaters love to clean plants, glass, and all other aquarium fixtures of multiple different kinds of algae which makes the very useful, plus they also eat dead plant debris which is an added bonus.

If you have this kind of fish you should actually have 2 of them as they enjoy living with their own species. Also you are going to need a tank that is at least 100 liters in size as they do require a fair amount of space because they can grow up to 14 cm in length. Siamese Algae Eaters are great for community tanks because they tend to be very friendly.

These fish also need lots of living plants, water with a pH level of 7, a temperature of 25 degrees Celsius, and the water needs to be well filtered and oxygenated.

Oto Catfish

These fish are perhaps the best kind of fish that you can get for the purposes of cleaning away algae from the plant matter in your fish tank. Their favorite type of algae to eat is brown algae, something that most other fish will stay away from.

They don’t grow very big, only about 5 cm in length, which makes them ideal for smaller and medium sized tanks. To make sure that each of the Oto Catfish have enough algae to eat, each one should have roughly 60 liters of water. Something that needs to be noted is that they don’t really eat fully grown algae, but they love to eat it when it just starts growing, which means that they are ideal for keeping the beginnings of algae growth under control. If there isn’t enough algae in your tank to sustain these fish you will need to feed them some blanched zucchini about once per week.

These guys don’t like to be alone and do well in groups of at least 4, as well they need to be in a planted aquarium because the algae they eat is found on the plants. Also the Oto Catfish needs water that is 25 degrees Celsius, has a pH level of 7, and needs water that is well filtered and oxygenated. These guys do well in community tanks and are quite friendly, the only problem being that larger predatory fish may not get along with them.

Bristlenose Plecos

The Bristlenose Peco is a type of catfish and they are voracious eaters. These things will eat pretty much any type of algae that they can get their sucker mouths on. That being said, of course this fish is a sucker mouth, something which makes them ideal algae eaters. If these fish don’t have enough algae to eat you will need to supplement their diet with algae tablets or other green foods because if they don’t have enough algae to feast on they will begin to eat the plant life in your aquarium.

These fish require water at about 25 degrees Celsius with a pH level of 7, as well the water needs to have a moderate current and be well oxygenated too. The Bristlenose Pleco is nocturnal and therefore likes dark spaces and areas where they can hide under during the daytime.

These fish are also very peaceful and usually don’t cause problems in community tanks unless they are threatened by larger predatory fish. As well, seeing as the Bristlenose can grow to up to 15 cm in length you will need to house this fish in quite a large tank for it to be comfortable.

Common Plecos

Common Plecos are sucker mouth fish that will feast on pretty much all types of algae that grows on plants, the substrate, and other aquarium fixtures (including wafers). One of the most important things to note is that these guys can grow up to 60 cm in length, meaning that they are only ideal for extremely large tanks which are over 300 liters in size.

These fish can be somewhat problematic because they do tend to eat many other smaller fish. Also if they don’t have enough algae to eat they will also begin to eat the plant life in the tank, not to mention that you will most likely need to feed them greens. A good thing about the Common Pleco is that they do very well in a variety of water parameters which makes them easy to house.

On the other hand they can be quite destructive due to their big heads and the ensuing head butts as well as their large tails, often ripping up plant life and substrate. The Common Pleco only does well in tanks with fish of the same size because if a fish fits in its mouth it will most likely eat it.


This is actually a whole species of fish and it includes Mollies, Guppies, and Platies, all of which are livebearers and all of which eat algae. It should be noted that all of these fish really only like to eat soft hair algae and a few other kinds of strand algae. They don’t do to well with other types of algae.

These fish are quite friendly and do well in community tanks. Also they are quite small which makes them ideal for smaller and medium sized fish tanks. As well they require medium water parameters just like most other fish on this list.

Are There Algae Eating Tropical Fish?

There are plenty of fish that are either tropical in nature or ideal for tropical fish tanks, most of which do a great job at eating algae. Just some of the fish that you can get for a tropical tank which will do a great job of eating various types of algae include the Otocinclus, Black Mollies, The Bristlenose, The Garra, American Flagfish, The Flying Fox, African Cichlids, Crossocheilus Reticulates, and Chaetostoma.

Other Algae Feeding Aquarium Inmates

There are several other animals that you can have in your aquarium that will do a bang up job of eating away at that nasty algae growth. These can include shrimp and snails so let’s take a quick look at the various other algae eaters.

The Amano Shrimp

This shrimp will eat virtually any type of algae that it can get its mouth on, plus it also eats old food and plant debris which is of course a bonus. The only kinds of algae they don’t eat is blue/green algae and green dot algae. These shrimp should not be kept in groups larger than 3.

They are also susceptible to certain chemical build ups in the water and thus the water needs to be changed on a weekly basis by 30 – 50 percent. Try not to feed them too much store bought food as that will make them want the algae less.

We have covered a separate guide on algae eating shrimp here.

Malaysian Trumpet Snail

These things are great for eating pretty much all types of algae as well as dead plant, animal, and food debris too. The main thing they are used for is actually to aerate the substrate which is yet another bonus. Malaysian Trumpet snails are good indicators of bad water quality because when the water is bad they will try to head to the top of the aquarium out of the water.

On a side note, these things need to be kept in waters that are fairly high in alkaline levels because they require it to rebuild their shells.

Nerite Snails

This is one of the most common snails to have in a fish tank because they are really pretty and they are known to eat beard algae as well as green spot algae, both of which can be very hard to remove. These animals do well in water that has a pH level of 7 or higher because they need the hard and alkaline filled water to have healthy shells. The downside to the Nerite Snail is that they often get eaten by larger fish.


If you had the question of “what fish eat algae?” you probably don’t have it anymore because this comprehensive guide on algae feeding fish should have given you all of the info that you need, both about algae and the fish and other aquatic animals that will help you get rid of it. If you have an algae problem the best solution is to get one of the options listed above.