Will Plecos Eat Other Fish?

Since Plecos are what’s known as opportunistic omnivores, they can comfortably live on both plant and animal matter. In other words, they’ll eat other fish, but only when the opportunity allows for it — like when the fish is dead in the tank. However, they prefer plants and algae.

So, with that in mind, this quick guide will go into detail about all you need to know about raising and taking care of your sweet Pleco fish. Let’s dive right in!

Will Plecos Eat Other Fish?

Plecos, scientifically known as Hypostomus Plecostomus, are great pet fish for beginner tank owners. That’s mainly because Plecos are a popular choice due to their gentle temperament and docile nature.

As such, it can be hard to believe that Plecos can be aggressive when they need to be. It might be just as difficult to imagine Plecos are able to eat their fellow neighbors in the tank as well.

The truth is, however, that Plecos, despite their colorful personalities, will ingest the protein of other fish without a problem—but only when the need arises for it though.

To put it simply, Plecos are opportunistic omnivores, meaning, they don’t turn to animal-based protein unless the opportunity is present for them. Plecos, in other words, won’t have meat simply because they must—as is the case with regular omnivores.

Plecos, then, will only eat other fish in certain circumstances. These instances may include some of the following:

  • Their fellow fish are dead or dying. As a result, they’ve sunk to the bottom of the tank and the Plecos will begin cleaning their bodies out by cleaning them.
  • The Plecos’ diet is insufficient, as in, they’re not getting enough protein to sustain them. They’ll need to make up for this deficiency by eating other fish.
  • You’ve provided your fish with an inhospitable tank environment that encourages aggression and leaves your fish cranky.

So, that said, if you don’t want your Pleco to attack or eat your other fish, make sure that you feed them well and that their homes closely imitate their original habitats.

On the other hand, though, you might want to be grateful for your Plecos. This breed works hard to clean out your tank from harmful algae and corpses of fallen fish.

Close up of a Plecostomus on Turquoise Gravel

Will Pleco Eat Baby Fish?

As established, Plecos will only eat fish if absolutely necessary. They’re not omnivores by nature and neither are they predators.

With that in mind, however, certain Pleco breeds show an inclination towards eating the small fish fry. For example, smaller Hypancistrus Plecos. Still, though, all Plecos stick to the rule of just eating dead or dying fish babies.

In that case, you don’t have to worry about keeping your breeding fish in the same tank as your Plecos. They won’t eat the newborn fry unless they’re stillborns or aren’t fed well after their birth.

The fact of the matter is that Plecos are great fish to keep in the aquarium while you breed livebearers. Why? Because they’ll keep the tank clean and continuously clear out the waters from scrapes and dead fish.

On top of that, Plecos are also adverse to eating their own babies. Filial cannibalism is common among this animal species so it’s rather refreshing to learn that Plecos don’t feed on their fry.

Why Do Plecos Eat Other Fish?

We briefly mentioned that Plecos are opportunistic. To put it simply, they need a circumstantial reason to eat other fish. If you eliminate these causes, you won’t have to worry about Plecos feeding on their fish friends.

Just keep in mind, however, that that won’t stop the Plecos from cleaning the tank from debris and dead fish when they have to.

Inhospitable Environment

An inhospitable tank is one of the main reasons that will push not only Plecos, but other laid-back fish to become aggressive.

You need your tank to be a steady place for your Plecos to live in. It shouldn’t be overcrowded, for instance, as this will encourage the fish to turn against each other just to eliminate the threat.

In other cases, if the tank’s water isn’t clean enough or there aren’t enough water parameters, then you’ll find that your fish become more stressed by the day. This stress will push them to feed on each other as well.

Scarcity of Food

A golden rule to remember when bringing up opportunistic omnivores such as Plecos is to always keep them well-fed. If their bodies are sustained enough and thriving, then they won’t feel the strong need to eat other fish.

Additionally, the more fish you have, the stronger the struggle will be among them for their survival. This competition will thus encourage all fish, especially Plecos, to show aggression and fight the others for food.


In some cases, the Plecos aren’t stressed, just sick. Similar to us, when they fall ill, Plecos become cranky and aggressive.

They won’t like other fish swimming around them when they’re ill and might perceive them as a threat then eat them.

What Fish Can Live with Plecos?

It’s important to reiterate that Plecos are docile and peaceful pet fish, meaning, they’ll have no issue with most other breeds of fish. Plecos mostly keep to themselves and don’t cause much trouble. Plus, they’re not aggressive unless the environment allows for it.

So, here’s a simple list of fish that can get along with Plecos:

  • Neon Tetra
  • Glass Catfish
  • Zebra Danio
  • Guppy
  • Platy
  • Molly
  • Hatchetfish
  • Arowana
  • Bamboo shrimp
  • Silver Dollar

Here are other names of fish species that are both Pleco and beginner-friendly:

  • Freshwater aquarium fish (guppies, mollies, etc.)
  • Swordtails
  • Corydoras
  • Gourami
  • Betta fish
  • Tiger barbs
  • Angelfish
  • Kuhli loach
  • Siamese algae eater
  • Otocinclus Catfish

In Summary

Will Plecos eat other fish? Yes, Plecos will eat other fish but only the dead ones. If Plecos’ fellow tank members are sick and on the verge of dying, Plecos will feed on those fish too.

That said, there are ways to avoid having your Plecos feeding on other fish. While providing Plecos with a safe environment won’t stop them from their cleaning duties, keeping them well-fed might avert them from eating other fish.