Do Cory Catfish eat algae?

Cory Catfish don’t eat algae because they are mostly carnivorous. If you look at their autonomy, more specifically their mouth, you can see that Corydoras aren’t made for eating algae.

If you have been keeping Cory Catfish for some time, you might have noticed your catfish scavenging throughout the tank looking for food. This is their way of finding food and how they adapted. You will never see them scraping of food or algae using their fragile mouth.

In comparison to for example a bristle nose pleco, which has special teeth and mechanisms for eating algae, Cory Catfish mainly rely on leftovers laying at the bottom of the tank. 

The mouth of this Royal pleco is made for grasping on wood. Photo by Jan
The mouth of this Royal pleco is made for grasping on wood. Photo by Jan
The mouth of this C. sterbai is made for digging for food

It’s the same reason cory catfish don’t eat snails. Their mouth is made specifically for eating small leftovers and they can’t eat hard or big foods (like snails).

But, there’s a way that cory catfish actually help prevent algae. How? Cory catfish are quite good cleaners and they will eat the leftovers other fish have not eaten.

This way, less food will pollute the water causing fewer algae. Be cautious though: like every fish, cory catfish poop. So you should still do water changes and buy a filter to support their waste!

Do Cory Catfish eat algae wafers?

Cory catfish will eat algae wafers and it’s a great source of food for them. However, it shouldn’t be fed as the main part of their diet, since they are carnivorous.

Algae wafers provide cory catfish with a great source of extra nutrients, being spirulina and plant-based proteins. These will be a good addition to the meat-based diet cory catfish should be fed.

My favorite algae wafers for cory catfish are Hikari Algae Wafers. They’re one of the most popular brands on the market and are available on Amazon. These wafers also have a high protein count, making them ideal for cory catfish.

Do Cory Catfish clean your tank?

Cory catfish are known for scavenging through the tank looking for food and leftovers. This will cause less food to pollute the water and ultimately a cleaner tank. However, cory catfish do poop too. As a result, you’ll still need to perform water changes and add a strong filter.

Cory catfish will eat the following things:

  • Leftover foods such as pellets, flakes, frozen foods
  • Dead fish
  • In some cases, fish poop
  • Fish/snail eggs

Different types of algae

Blue-green algae (Cyano Bacteria)

This alga is one of the best-known algae in the hobby. Unfortunately, not because it’s good or beautiful but quite the opposite. 

When not contained, it can take of your aquarium and cause the death of your fish. There even have been recorded cases where humans died of this bacteria.

It thrives in slow, nutrient-rich water and no species of fish is known to eat it. This makes it hard to naturally remove from your tank.

The first thing to do, like in most problematic situations, is to check your water parameters. You should specifically pay attention to nitrates and ammonia. If you notice abnormally high values, perform more water changes and clean your filter.

The last thing you can do is add hydrogen peroxide. This will kill the cyanobacteria. Be careful though, because if you use too much it might kill other beneficial bacteria. 

Brown algae

Brown algae are just like blue-green algae a fairly recognizable type of algae. As their name says, they’re brown algae you’ll most likely find on your glass, but they will also appear on plants or gravel.

Unlike the blue-green algae, there are quite a few types of fish that find it to be a nice snack. The Sailfin pleco is a good example. It loves eating algae and more specifically brown algae.

Other plecos like bristlenose plecos will also eat this type of algae.

In almost every new aquarium, brown algae will occur and this isn’t necessarily a bad sign. It’s only a sign that your tank is alive and that things have to balance out. It will most likely disappear after a couple of weeks.

It’s easy to scrape off this type of algae, but a permanent solution should be searched if it keeps occurring. Here are some actions you can take to prevent brown algae:

  • Enhance the lighting in your tank
  • Change water regularly
  • Clean your filter regularly and don’t overfeed

Blanket weed

People who have a pond will certainly recognize this type of algae. It’s caused by low CO2 levels, low water movements, and low nutrients. 

These algae can easily be removed by hand, although they can stick to rocks and form a plague.

Not many fish will eat this type of algae. Only goldfish or carp seem to like it. Shrimp on the other hand like this sort of algae and will happily eat it.

Beard Algae / Black Bush Algae

This species of algae is hated by many aquarists because it’s so hard to get rid of. It’s caused by slow water movements, low CO2 levels, or too much lighting.

On top of it being hard to remove from your tank, there aren’t a lot of fish that eat this type of algae. Only Siamese algae eaters are known to eat it.

To prevent beard alg in your aquarium, do the following things:

  • Make sure there is water movement in the entire tank. All plants should move with the current
  • Dim lighting
  • Add CO2 to your tank.

After doing one or more of the following things, beard algae will not disappear immediately. You will have to manually remove the beard algae. Here are some tips:

  • If it’s on the glass, scrape it off using a razor
  • If it’s on hard structures like wood or stones, use an old toothbrush or tweezers
  • Remove heavily damaged leaves. Healthy plants will make new leaves.

Hair Algae

Hair algae aren’t one specific species of algae. It’s just referring to all the algae that look like wet hair when taken out of the aquarium. Not only do they grow super rapidly, but they’re also quite hard to get rid of.

You can remove them by hand, but the chances of getting rid of them permanently are small this way.

Like with all algae, you’ll have to look at the causes of the problem. In most cases, these algae will come as a result of too much iron or other access nutrients, as well as too much lighting.

What do Corydoras eat?

Does it come as a surprise if I say many people forget to feed their cory catfish? Not only because they think cory catfish eat algae, but also because they think these fish can survive on leftovers. Even though cory catfish are hardy beginner fish, they still need a varied diet.

Cory catfish are carnivorous fish and should be fed a varied diet of different meat-based foods. This includes live foods such as bloodworms or mosquito larvae, but also dried foods like Dr. Bassleer or frozen foods. Additionally, you can feed algae wafers.

I recommend investing in high-quality dried food, like Dr. Bassleer, and feeding a variety of food. Just like us humans, fish need different nutrients and vitamins to stay healthy. By investing in a variety of high-quality fish foods you will achieve this.

If you want to breed cory catfish, it’s useful feeding them live foods. These foods will contain lots of protein and bring up the natural instinct of cory catfish. By feeding these live foods twice a day while performing daily water changes, cory catfish are likely to spawn.

Alternative algae-eater fish

As you now know, cory catfish aren’t the ideal algae eaters for in your aquairum. Here are five species I recommend as an alternative to cory catfish.

Please keep in mind that you should never buy a fish solely to get rid of algae. They’re not reliable, poop (increasing the bioload of your tank) and have to be able to live with the other inhabitants of the tank.

1. Bristlenose pleco

An albino bristlenose pleco male. Photo by Thomas Siems

Who doesn’t know the bristlenose pleco, right? Going under different names such as suckermouth pleco or just pleco, it’s one of the most popular fish in the aquarium hobby.

Even though many pleco species eat algae, bristlenose plecos are one of the easiest (and smallest!) plecos to keep in your tank.

Bristlenose plecos eat vegetables as a big part of their diet, but you can also feed them some meaty foods. Even though they’re not the most efficient algae eaters, especially young fish will eat algae in your tank. 

Care level: easy

Compatible with Corydoras: yes

Bristlenose pleco size: +- 5 inches

Min. tank size: 20 gallons

2. Otocinclus catfish

Photo by AJC1

Otocinclus catfish are calm and peaceful fish that are great algae eaters. Because of their tiny size, you can assemble a real Otocinclus army to combat the algae in your tank. Especially brown algae are their favorite.

Overall, Otocinclus aren’t that difficult to keep, but they can be sensitive to fluctuating water parameters.

Care level: some experience required

Compatible with Corydoras: yes

Size: <2 inches

Min. tank size: 20 gallons

3. Cherry shrimp

Red cherry shrimp

Who doesn’t love shrimp, right?

Cherry shrimp are one of my all-time favorite animals to put in a tank. These shrimp are beautiful, reproduce super fast, and are easy to keep. If you have too many, just sell them to a local fish store or feed them to other fish. that being said, populations will balance out.

Cherry shrimp are very calm and peaceful. Maybe a little too peaceful, because they can be a nice snack for many species.

Care level: easy

Compatible with Corydoras: yes

Size: <1.5 inches

Min. tank size: 5 gallons

4. Snails

Ramhorn and pond snails, including our curious Betta named Berta and some shrimp.

There are tons of snail species available: from big mystery snails to tiny trumpet snails. Most snails are exceptional algae eaters that are great cleaners.

Apart from eating algae, they eat leftovers and dead plant material and sometimes even fish poop or dead fish. Overall, a great cleaner with a small bioload.

There are some species of snails like Assasin snails that don’t eat plant-based foods, but are fully carnivorous and eat other snails. Most species however are very peaceful and can live with basically any other fish species.

I love snails so much that I even decided to write an entire article on it, named Can Cory Catfish and Snails live together?

Care level: easy

Compatible with Corydoras: yes

Size: 0.5-2 inches

Min. tank size: 5 gallons

5. Florida Flag Fish

This species is a great addition if you’re looking for a reliable algae eater. It does prefer colder water (it’s native to North America), so non-heated tanks are perfect. As we discussed earlier, there aren’t many fish that eat Black Bush Algae, but this is a fish that actually does!

If you have delicate plants, it might not be a good choice, since this fish can damage the plant will eating algae.

Care level: easy

Compatible with Corydoras: yes, Cory Catfish that prefer lower temperatures.

Size: 0.5-2 inches

Min. tank size: 20 gallons (pair)



Cory catfish are not good algae eaters and the main part of their diet consists of meat-based foods. Cory catfish do eat algae wafers, but they shouldn’t be fed as their main source of food.

Great foods for cory catfish are pellets, frozen foods, and live foods for spawning.

If you do want a fish that eats algae, alternatives are bristlenose plecos shrimp, snails otocinclus, snails and florida flag fish. All of them can live with cory catfish and are relatively easy.