Why Did My Cory Catfish Disappeared?

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Corydoras are bottom-to-mid dwellers that like to live in groups and showcase an energetic and lively presence.

You’re used to seeing them swimming slowly near the substrate and among plants and rocks, constantly searching for food on the substrate.

But what happens if you notice one or more of your Corydoras missing? This can easily confuse more inexperienced aquarists, given that the tank is a closed and secure system. Where would the fish go, right?

Fortunately for you, I have 5 potential answers for you to consider, so let’s jump right in!

5 Reasons Cory Catfish Disappeared

If one of your Corydoras seems to have just vanished into thin…water, consider the following 5 potential explanations:

1. Cory Catfish is Hiding

Ideally, your cory catfish’s habitat has a lot of plants, rocks, and other substrate decorations for the catfish to use when necessary.

These are timid fish that enjoy dim-lit environments with a variety of hiding places available. It’s not uncommon for your catfish to hide, either in the substrate or in a cave somewhere, out of sight.

The fish’s color pattern also allows it to render itself invisible in a lush environment with a lot of decorating elements all over the place.

The catfish can hide for a variety of reasons, including playing, resting, or even when stressed, looking for some time off.

If you can’t see your fish anywhere, look into all of the nooks and crannies nearby to catch a glimpse of the tail or head.

Or simply wait it out a bit. If everything’s fine and your fish is hiding, it will come out shortly to feed.

2. Cory Catfish Got Stuck in the Filter Intake

Few people expect this, but it’s actually quite a common problem. Corydoras can get as small as 1 inch, which can easily cause them to get sucked off by the filter’s intake.

This can cause a variety of problems, with the fish’s death being, interestingly enough, the milder one. The fish’s carcass will both clog the filter and decay out of sight, creating excess ammonia and nitrites.

This will cause the filtration system to poison the very environment it’s supposed to clean.

So, you should always check the filter’s intake if you notice one of your small catfishes missing.

Furthermore, to prevent this issue altogether, consider:

  • Securing the filter’s intake – Use a sponge or a piece of fine material to cover the filter’s intake. This will prevent the fish from going in even if it swims in the intake’s operating range. Just remember not to block the intake completely, preventing the filter from doing its job. Plus, you should always verify and change the sponge/material regularly since it will accumulate dirt and residues fast.
  • The intake’s placement – This is another great point to consider. Avoid placing the intake near the catfish’s dwelling area. Keep it in the tank’s middle area to prevent it from sucking in fish or substrate, which can clog the filtration unit. Also, keep it away from plants for the same reasons.
  • Managing the filter’s power – Corydoras like to live in slow-moving waters, so there’s no need for excessive filtration power. Especially if you have small Corydoras that can get sucked in due to the high suction effect. Manage the filter’s power properly to provide your Corydoras with a stable, healthy, and, most importantly, safe habitat.

3. Cory Catfish Jumped Out

I’m sure you didn’t see this one coming. After all, nobody expects their bottom-dwellers to jump out of the tank, given that the fish shouldn’t go near the water’s surface anyway. Corydoras are different, though.

These fish exhibit what’s known as intestinal breathing, which is a common catfish feature. In short, the catfish’s intestinal wall is adapted to process oxygen molecules from the atmosphere.

This means that your catfish will sometimes swim to the water surface for a swift gulp of air and then dive back into its safe space.

The fish’s contact with the water surface is less than a second, which is enough for the Corydoras to take in a healthy dose of oxygen. The oxygen is then passed through the intestine, where local capillaries will process and use it.

This evolutionary feature allows the catfish to thrive even in suboptimal water conditions with improper oxygenation.

I’ve detailed all of this to show that Corydoras can actually reach the water surface occasionally.

Most importantly, they tend to do so more frequently if their water is poorly oxygenated. In those scenarios, the catfish can actually jump out of the tank due to the stress related to poor water conditions or insufficient oxygenation.

I recommend 2 solutions in this sense:

  • Keep water quality high – Just because your catfish can adapt to poor water conditions doesn’t mean that you should test its abilities. Your goal should be to provide your catfish with the best life it can have. This includes creating a stable and well-oxygenated environment to keep your fish healthy and calm.
  • Secure the tank – Consider a tank lid if your catfish showcases a more frequent surface-diving behavior, despite the optimal oxygen levels in the water. Not all catfish are alike. Just make sure that the lid has holes for proper gaseous exchange at the water surface.

4. Cory Catfish Got Eaten

This is a serious concern in community tanks, especially where different fish species share the same space.

You ideally want to house your catfish with fish that are peaceful and similar in size to your Corydoras. If that’s not the case, some of the tank inhabitants might attack and even eat your catfish.

Your catfish may also die for various reasons, at which point other fish can consume the carcass.

Or another pet you have in your home can simply catch the fish during one of its regular surface incursions and dispose of it before anyone can notice.

It can be difficult to tell where your catfish has gone if there’s no sign of it.

So, consider the following solutions:

  • Tank lid – A well-aerated lid will prevent the fish from jumping out and keep Corydoras safe from any potential catfish-eating pets.
  • Adequate tankmates – Only house your Corydoras with peaceful fish that match your catfish in terms of temperament, food, and water requirements, and, most importantly, size. This will minimize the risk of other fish attacking the more peaceful and defenseless catfish.
  • Constant supervision – You should always check your fish’s dynamics and interactions in the tank to make sure they remain cordial. Sometimes, even presumably peaceful species can create tensions in the tank. They may not kill your catfish directly, but they can stress them out, and stress can kill them.

5. Cory Catfish Just Died

Sometimes, things simply take the wrong turn, despite all your precautions. Fish get sick and die, as this is part of how nature works.

There are 2 scenarios to consider when that happens:

  • The fish gets eaten – A lot of fish won’t attack and eat their live tankmates, but they don’t mind eating their dead carcasses. If your catfish dies and you’re not there to witness it, other tank inhabitants can dispose of the body before you know it.
  • The fish simply decays away – This is a dangerous prospect because decaying fish poison the water. This generally happens in lush aquatic ecosystems where it can be difficult to notice a dead 1-2-inch catfish. The fish’s corpse can easily get lost in the scenery, quickly turning into an environmental hazard.

You can avoid this situation by, first, providing the fish with optimal water conditions, maintenance, and care and, second, always monitoring the habitat. The latter allows you to detect any dead fish in time and remove them before they become a liability.

Do Cory Catfish Bury Themselves?

Yes, they do. This is why Corydoras always fare better in sandy substrates. The sand will keep all the food on the surface, allowing the catfish to find it easier, and allow the fish to bury itself in it occasionally.

Corydoras typically do that for entertainment purposes, as it calms them down and keeps them in good spirits.

However, consider the dangers associated with sandy substrates before going there.

Ammonia pockets are a real threat, given that they can quickly poison the fish, the plants, and the entire environment.

To prevent the formation of ammonia pockets:

  • Stir and vacuum the substrate – Sand needs to be regularly stirred to prevent anaerobic pockets. Don’t go overboard with it. Stir it gently using a long and thin tool, careful not to blast too many particles into the water column. These can get sucked into the filter and clog the system sooner. Vacuuming the substrate regularly is also great in this sense. Not only will it clean the substrate, but it will also drastically minimize the risk of anaerobic pockets.
  • Snails – Add snails to your tank. These digging creatures will burrow into the substrate in search of food and shelter. Just make sure you avoid small snail species or baby snails that your Corydoras could eat. Because they will. I recommend mystery snails or any other large species that Corydoras won’t view as prey.
  • Live plants – Live plants are great in this sense because their root system prevents the formation of anaerobic pockets. Live plants are also great at consuming excess ammonia, nitrites, and nitrates, keeping the water cleaner and healthier.
  • Regular tank maintenance and water changes – You should always clean the tank and perform regular water changes to dilute ammonia and freshen up the ecosystem.

How to Find Missing Cory Catfish?

If your Corydoras is nowhere to be seen, consider the following:

  • Check outside of the tank – Interestingly enough, this should be your first move. If your fish has jumped out, it doesn’t have much time left. Look around the tank on the floor or under furniture, where it appears your fish could’ve ended. These slippery and wiggly creatures can reach even the most unexpected locations.
  • Check inside of the tank – Look through plants and rocks to see whether your Corydoras is simply hiding. This will also allow you to detect sick fish that hide out of discomfort and stress.

If the fish is simply gone, consider any of the explanations I’ve offered in today’s article.

To summarize:

  • It jumped out of the tank, and a pet got it
  • A pet fished it from the tank itself during one of the catfish’s surface incursions
  • The fish died, and other tank occupants ate it
  • The tank inhabitants ate it while still alive
  • The catfish died and decayed out of sight

How to Dispose of a Dead Cory Catfish?

There are several ways of disposing of your dead Corydoras, such as:

  • The trashcan – This is as easy as it sounds. Before throwing the fish in the trash, though, place it in a zip-locked bag. This will prevent it from contaminating the surroundings and decrease the fish’s olfactory print so other predators won’t sense it.
  • Bury it – You can bury your fish in your backyard, or somewhere you know other pets won’t reach it. The fish’s decomposing body will feed the surrounding land, which is a definite win.
  • Cremate it – This is probably the safest and most hygienic method of them all. Cremating the fish is ideal if you have the means for it, as it eliminates all pathogens that colonize the dead fish’s body.

The following are no-no methods of disposing of dead fish, catfish included:

  • Feed them to your pets – The dead fish contains a variety of potentially deadly pathogens that won’t sit great with your pets.
  • Flush them down the toilet – This allows the fish to contaminate the environment.
  • Simply throw it away – You never know which of your pets can find the dead fish, and we’ve already discussed the problems with that.


Whenever one of your fishes disappears, you need some proper detective work to figure out what’s happened.

I hope my today’s Sherlockian article can serve you well in this sense.

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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