You may have seen it even at a pet store.

A fish eating another fish’s fecal matter is a disgusting thing to us, but to them, it’s just another natural instinct.

Sometimes fish will eat fecal matter to identify whether the fecal matter belongs to another fish or itself. Fish actually have the ability to distinguish this, and it helps identify if another fish is present in the tank or not.

Most fish spit the fecal matter out, but some swallow it.

Sadly, fish are not the brightest of creatures in the world, and if they come across the fecal matter again, it may eat the fecal matter again without realizing it already did.

Fish are very simple-minded creatures, but they are beautiful to see in their tanks. In order to learn more about other odd things fish can do, you can visit the website here that belongs to the veterinary clinic Katy.