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Why Does My Cory Catfish Have a White Fungus? (3 Causes)

Why Does My Cory Catfish Have a White Fungus? (3 Causes)

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This post is written to the author's best knowledge and is not intended to be used in place of veterinary advice. In addition, this post may contain affiliate links. As an Amazon Associate I earn from qualifying purchases.

Most agree that cory catfish are pretty easy to take care of. These fish are hardy and are considered to be good options for beginners.

If you do your best to care for these fish, then they should thrive in your fish tank. Mistakes do happen, though, and sometimes you might notice odd things will happen to the fish.

For example, you might see that the fish has some type of white fungus on it. If this occurs, what does it mean?

Read on to learn about cory catfish and white fungus. You’ll have a much better understanding of what is actually happening once you’ve read all of the information.

Fungal Infection

Generally, when a cory catfish develops some type of white fuzz on its body, it’s a sign that it has been infected. These types of fungal infections can happen to many different types of fish.

There are quite a few things that could be going wrong in your fish tank. It isn’t a good sign for the fish to have a fungal infection like this.

It means that you’re doing something wrong in the tank. If you’re new to caring for fish, then you might simply be adjusting and figuring out what you’re supposed to do.

Below, you’ll learn about some of the things that might be going on that are causing the fish to get infected. Later, you’ll learn about how to treat fungal infections.

1 – Dirty Water

Man Cleaning a Fish Tank

Dirty water is the likely cause of fungal infections in your fish. It’s very possible that your fish tank isn’t as clean as it should be.

When you’re caring for fish, it’s imperative to monitor the water parameters. You need to do your best to keep the water parameters in the right range so that the fish can stay healthy.

Sometimes new fish tank owners forget to monitor the water parameters. You might not be testing the water to see what the pH balance is regularly enough.

When the pH balance is not in the right range, it’s going to cause problems for the fish. It’s even possible for fish to die due to being in water that isn’t right for them.

Also, this can cause the ammonia, nitrate, and nitrite levels to get too high. Heightened levels of nitrates can easily kill catfish.

If things are a bit too high, then it can make it more likely that the fish will get infected by bacteria. The fish tank might be too dirty due to you not changing the water often enough.

It’s recommended to change 15% of the water each week to keep things in check. Good habits such as this will make it easier to keep the fish safe.

3 – Overcrowded Fish Tank

Cory Catfish in Community Tank With Neon Tetras in Background

Crowded fish tanks are more likely to have issues with fungal infections. Simply put, when a fish tank is crammed with too many fish, it’s going to get dirty fast.

It’ll be a whole lot tougher to keep the water in the fish tank clean. Cory catfish are considered to be excellent community tank fish, but you aren’t supposed to keep them in fish tanks that are crowded with fish.

You want to make sure that you give the fish enough space to be able to move around properly. It’d actually be easier to care for a bigger fish tank that isn’t crowded than it would be to take care of a small and crowded tank.

Always do a bit of research to ensure that you have enough room for the fish that you buy. Overcrowding a fish tank will cause fish to get stressed, and this will make it more likely that the fish will get infected.

3 – Overfeeding the Fish

Peppered Cory Catfish Eating Algae Off of a Plant

Feeding the fish too much can make the water dirty as well. Sometimes people accidentally feed their fish more than they’re supposed to.

You do want to feed your fish every single day, but you don’t want to go overboard. Feeding the fish too much will make them poop a lot, and this will make the water very dirty.

When feeding cory catfish, it’s best to feed them twice per day. Each time you feed them, you should give them as much food as they can eat within three minutes.

If you stick to feeding the cory catfish like this, then you’ll have a good experience. It should keep the fish healthy without making them poop more than they should.

How to Treat Fungal Infections

Treating fungal infections will actually be pretty easy overall. However, you’re going to want to solve the issues in the fish tank that made it possible for the fish to get infected.

Test the water parameters and try to get an idea of what is going on. You might need to use chemicals to adjust the pH balance and get things back to normal.

You will be able to treat the fish using various types of medication. It’s easy to go to pet stores and buy fungal cures or bacterial disease treatments.

It should help to clear up the fungal infection so that the fish can get better. Continue to monitor the fish and give it high-quality foods so that its condition will improve.

If you’re able to treat the fish properly and maintain good water conditions, the fish will be just fine. Of course, if you don’t treat the fungal infection, it will eventually kill the fish.

Final Thoughts

Now that you know why cory catfish might have white fungus appear on their bodies, it’ll be easier to understand how to proceed. You can treat the fish and get it to feel better.

First, you’ll need to fix the conditions in the tank that are causing the problems. Then it’ll be easier to treat the fish using antifungal or antibacterial medications.

Try to do a better job of monitoring the water parameters moving forward. If you can avoid overcrowding the fish tank and overfeeding the fish, then you should have a simple time avoiding fungal infections and many other common diseases and illnesses in your cory catfish.

Cory catfish are hardy fish that can do well in your tank when you put the necessary effort in. Just try to avoid making big mistakes and everything should be fine.

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Wednesday 21st of September 2022

My Corry catfish (excuse me if I spelled that wrong) has white fungus on its eye I thought it might be popy eye but I can't see the eye


Friday 27th of May 2022

What fungal treatments would you advise for corydoras?


Tuesday 31st of May 2022

Hi there, you could try either API General Cure or Fungal Cure. You can probably find these products locally, but here are the links just in case:

General Cure: Fungal Cure: