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Why Is My Cory Catfish Killing Other Fish?

Why Is My Cory Catfish Killing Other Fish?

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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.

Many people buy cory catfish for their fish tanks specifically because of how peaceful they are. They’re considered to be among the best options for community fish tanks.

They’re bottom-dwelling fish that hang out at the bottom of the fish tank and mind their own business. The peaceful nature of the fish means that they won’t generally bother other fish.

What if you have an aggressive cory catfish in your fish tank, though? Could a cory catfish kill other fish in the tank?

Read on to learn about what could be happening that would cause a cory catfish to become aggressive. This should help you to decide how to best move forward.

Do Cory Catfish Sting?

Pair of Horseman's Cory Catfish Swimming in Aquarium

Yes, it is possible that a cory catfish could sting you or another fish. Whether or not the term “sting” is the right word for this is a topic that is debated among enthusiasts, though.

Cory catfish can poke you with their spines. These spines protrude from an area near the eyes of the fish.

They come out when the fish feel scared or excited. When you get poked with one of these spines, it’ll inject a mild type of toxin.

It isn’t really harmful to humans, but it does have the potential to hurt quite a bit. This is a good reason not to try to handle a cory catfish.

Of course, you should never have a reason to try to do that. A cory catfish might use its spines in self-defense if threatened by another fish.

There is the potential that the toxins released by the cory catfish could kill another fish. However, it is not typical for cory catfish to kill tank mates.

Are Cory Catfish Aggressive?

No, cory catfish are not generally aggressive fish. In fact, they’re considered to be some of the most peaceful fish that you can buy.

This is why they’re considered to be such great community aquarium members. They’re so peaceful that they will usually never attack or even bother other fish in a tank.

It would be highly unusual for a cory catfish to willfully kill another fish in the aquarium. It’s just not in the nature of these fish to do such things.

Generally, cory catfish are going to be so peaceful that they will run and hide rather than fight back. In fact, these fish are in danger of being bullied by many other fish.

It isn’t impossible that a cory catfish could kill another fish in the tank. It’s just not something that would be very common.

Always Pick Appropriate Tank Mates

Cory Catfish in Community Tank With Neon Tetras in Background

It’s imperative to take the time to pick appropriate tank mates for the cory catfish. These fish are great community tank fish, but they can only be put in tanks with fish that they are compatible with.

Some beginners make the mistake of thinking that cory catfish can be placed in community tanks with almost any type of freshwater fish. Aggressive fish can bully the cory catfish, and this can create various problems.

Taking the time to do the necessary research before setting up a community tank will be for the best. You want to pick fish that will get along well with the cory catfish.

There are so many great types of fish that can be put in fish tanks with cory catfish. You can put them in community aquariums with mollies, bettas, angelfish, and even amano shrimp.

So you won’t be lacking choices when it comes to putting together a great community aquarium. You just need to ensure the compatibility of all of the fish that you choose to place in the tank.

Avoid Overcrowding the Fish Tank

Have you put way too many fish in the fish tank? Pretty much all fish are going to feel uneasy and agitated when placed in fish tanks that are overcrowded.

You need to ensure that all of the fish have enough room to feel comfortable. Otherwise, it can lead to conflicts in the tank.

Cory catfish are peaceful, but they can become more stressed than usual when placed in overcrowded tanks. Some have noted that cory catfish might chase other fish a bit if placed in small tanks.

The chasing behavior may or may not happen. However, it’s a bad idea to put the fish in a tank that is too small no matter what.

Put Hiding Spots in the Tank

Three Stripe Corydoras Hiding Under a Rock

Putting hiding spots in the tank will help the cory catfish to feel more at ease. They like having aquatic plants that they can use to hide from other fish.

You shouldn’t put the cory catfish in a tank that doesn’t have plants. It would make them feel uncomfortable and too exposed.

These fish need to have plants to feel comfortable with the environment. It’s also imperative to give the cory catfish substrate that they can sift through safely such as sand.

Be sure to set the tank up properly for the cory catfish. Doing so should reduce the chances of them coming into conflict with other fish in the tank.

Final Thoughts

Cory catfish usually won’t come into conflict with other fish in a community tank setting. They’re such peaceful fish that they’re in danger of being bullied by other fish.

Of course, cory catfish aren’t defenseless. They can “sting” other fish with the protective spines that they possess.

They can release toxins that can be harmful to certain types of fish. There is a chance that these toxins could kill another fish.

Since cory catfish are so peaceful, it’s pretty unlikely that you’ll ever see one kill another fish in the tank. If this does happen, then it might be due to there being problems with the tank mates that you have chosen for the cory catfish.

Always be sure to pick appropriate tank mates that are compatible with the cory catfish. Also, remember to give the fish enough space in the tank so that they can feel comfortable.

Give the cory catfish hiding spots by putting aquatic plants in the tank, too. If you take these precautions, then it’s very unlikely that you’ll see a cory catfish kill one of its tank mates.

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