Do Corydoras Kill Other Fish?

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Corydoras are notorious bottom-dwelling catfish that showcase increased adaptability and resilience and enjoy a peaceful community life.

Although these fish can live solo, they much prefer a social life in the company of other fish, including specimens of their own species.

This brings us to today’s topic, which is the notion that Corydoras can attack or kill other fish. Is this true, or is it just an internet myth, painting a different picture of the cory catfish than what we’re used to?

Let’s have a look!

How Cory Catfish Can Kill Another Fish?

I’ll go ahead and say that Corydoras will never kill other fish intentionally. But it can happen unintentionally.

You see, Corydoras are peaceful and docile animals that like to avoid violence and have no interest in territorial or hierarchical battles. That being said, they can sometimes be unable to avoid tensions, leading them to become victims of bullying.

Corydoras don’t have many defense mechanisms, but they do have some; aside from their ability to run and hide. We’re talking about their fine pectoral and dorsal spines located on their fins.

You almost can’t see these with the naked eye, but they’re there, and they’re more visible in the case of larger specimens.

Similar spines are also present around the fish’s head.

The Corydoras will use these to poke any potential attackers and inject them with a rather mild poison that’s not meant to kill them.

These catfish can also release the poison in the water when stressed or threatened. The poison isn’t dangerous, but the actual stabbing can be.

The wound isn’t necessarily deep or life-threatening, but any skin abrasion or cut opens the door to the billions of bacteria swimming in the water. This can lead to secondary infections and death if untreated.

Other than that, Corydoras have no incentive to kill other fish unless we’re maybe talking about tiny fish fry.

These often turn into food for much larger fish, Corydoras included.

Are Corydoras Aggressive?

No, not at all. Corydoras are peaceful and timid fish that like dim-lit environments with a lot of hiding areas.

They prefer to avoid all tensions and will flee in case any fish tries to attack or bully them.

This makes Corydoras perfect for all peaceful community tanks.

This being said, you should most likely be concerned for your Corydoras rather than the other fish.

It’s the catfish that will most likely be a victim of aggression in a community setup, which brings us to the next section.

How to Make Corydoras Feel Safe?

Most people take catfish for granted for 2 primary reasons:

  1. Their low profile – Corydoras spend their time hiding around the substrate and between plants. So, they’re not as flashy or in-your-face as other fish, causing many people to forget their critical role in the ecosystem.
  2. Their anatomical defensive capabilities – It’s okay, the catfish will be fine. After all, it’s armor-plated. Unfortunately, that’s not how it works. Even if the hardened scales make the catfish less prone to physical injuries, the constant tensions and bullying can cause stress and the fish are not equipped to handle that.

So, you should consider the following when looking to keep your catfish safe and happy:

Choose Good Tankmates

Avoid aggressive and territorial species that are likely to target your catfish for bullying purposes. Also, stay away from aggressive eaters, especially bottom feeders that could bring food competition to your chill catfish.

The ideal tankmates for Corydoras are other Corydoras. These are schooling fish that find peace and comfort in the company of each other.

Living in a school allows Corydoras to adapt to a community setup easier and minimize tensions between the different species.

Consider mollies, swordtails, guppies, tetras, plecos, shrimp, and larger snails for a sample of more compatible tankmates for your Corydoras.

In other words, any peaceful community creature you can find.

Provide Hiding Spaces

Corydoras are timid by nature, so they require a cozy and secure environment to leave in pace. Keep the lights low and provide your catfish with a variety of hiding areas.

The substrate is the fish’s natural refuge, as catfish often bury themselves in the sand for hunting or resting purposes.

Live plants are also a must due to their beneficial environmental impact and their passive role as hiding elements. Catfish rely on live plants to break line of sight with other tank companions in case of need.

Finally, rock structures are a welcome addition, allowing the caves system and various crevices to serve as valuable, safe spaces for catfish. Other fish will use them as well, providing everyone with good exploration material.

Not to mention, rocks also serve as a playground for various microorganisms and algae, which can serve as food for a variety of fish species, including catfish.

Keep them in a Group

Corydoras fare best in groups, so you need to consider at least 5-6 specimens for your community aquarium. These catfish rely on each other to keep themselves safe and at ease in their habitat.

Just make sure that the fish have sufficient space, food, and hiding spots to use when necessary. Corydoras require a combination of plants, rocky hiding areas, and open swimming grounds to live a balanced life over the years.

Your job is to make sure all catfish can benefit from all these different planes equally to prevent stress or, even worse, overcrowding.

Don’t Overcrowd the Tank

It’s easy for inexperienced aquarists to overcrowd their catfish aquarium, specifically because catfish don’t seem to need much space.

After all, they spend their time on the substrate, don’t move that much, and don’t seem to use the rest of the tank. This can lead to the misconception that catfish don’t actually need too much space.

And they don’t, for the most part, but they, too, have their own space requirements to respect. Overcrowding your catfish and fish, in general, can have devastating consequences for the fish community and the environment as a whole.

Overcrowding is responsible for the following problems:

  • High fish stress – Constantly bumping into each other will cause the fish to become stressed. This leads to an unhealthy, tension-filled living space that benefits no one.
  • Poorer water quality – Insufficient tank space equals excess fish waste, excess food residues, and degrading water quality. Overcrowded tanks require much more maintenance and frequent water changes than optimized setups. Skip the maintenance day once, and your fish will experience rapid ammonia and nitrite increases that can prove fatal fast.
  • Increased fish aggression – Some fish species are docile and peaceful but can turn aggressive and territorial when overcrowded. And violence is never good in any fish community.

Always ensure sufficient space for all tank inhabitants, and remember that doing so requires careful planning.

Different fish species come with different requirements, so you have some logistics work to figure out before kick-starting the tank.


Corydoras are the farthest away from the image of a killer fish as you can get. These timid bottom dwellers won’t bother any of their tankmates as they like to keep a low profile and stay out of trouble.

If anything, they are most likely to become victims themselves under certain circumstances.

Fortunately, you’ve read today’s article, so you now know how to avoid and manage those situations properly.

Author Image Fabian
I’m Fabian, aquarium fish breeder and founder of this website. I’ve been keeping fish, since I was a kid. On this blog, I share a lot of information about the aquarium hobby and various fish species that I like. Please leave a comment if you have any question.
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