Do Betta Eat Guppy Fry?

Betta and guppies are both beautiful fish with long, flowing fins. Keeping them together seems like a no-brainer (though isn’t necessarily). But what about the baby guppies?

Betta fish are carnivorous and will eat guppy fry, as long as they are small enough to fit  them in their mouths.  You can protect them by providing places to hide, such as thick plants like java moss.  Guppies reproduce fast enough that some are likely to still make it to adulthood, however.

For those of you who are hoping to add a betta to your guppy tank to control the reproduction rate, bettas will eat some but probably not all of the fry, so bettas may work to slow down your guppies’ rate of reproduction. They’ll probably attack your male guppies due to their flashy fins, however.

Why Do Betta Fish Eat Guppy Fry?

Betta can be pretty moody fish, especially when it comes to other fish being allowed into their habitat. In some cases, there are things you can do to introduce them successfully and get them to behave in a more civilized manner towards the other fish in their aquarium.

When it comes to baby fish, however, betta will absolutely eat any of them it can fit in its mouth. (And there’s not much you can do to stop it.) The reason is simple.

  • Betta’s are carnivores. It has pretty much become a truism of evolutionary marine biology that the bigger the marine animal, the more likely it is that it’s a carnivore. Betta’s are among the small throng of marine animals that don’t adhere to this rule. 

Therefore, owners of betta fish need to bear this in mind whenever they want to include another fish species inside their home aquariums. Don’t underestimate you’re bettas willingness to eat any fish small enough to fit in its mouth. Even when the guppies get too big to be eaten, they still aren’t safe.

  • Betta fish are aggressive. Even beyond just their carnivorous diet, betta fish are notoriously aggressive. They need to be, both to stave off possible predators on account of their small size and to ensure that they can maintain territory in the wild. These traits, coupled with the enclosed spaces of a mini aquarium and small, viable prey like guppy fry, makes for a very dangerous combination of factors.
  • Guppy fry present easy prey. Being the offspring of an already miniature species of fish with limited aggressive tendencies and a plant-based diet, guppy fry are very easily preyed on. Even taking betta fish out of the equation, guppy fry would still be preyed by a number of carnivorous fish small enough to fit into a tank. In fact, in quite a significant number of cases, mature guppy fish (including the parent’s of the guppy fry offspring) have been known to eat guppy fry whenever the opportunity presents.
  • Betta fish are highly territorial. Territoriality and the problems caused by it is one of the animal kingdoms’ ever-present realities. As such it is fairly unavoidable and mini aquariums are no different, especially in cases where prey and predator populations are living in the same small box. Therefore, betta fish may eat guppy fry, particularly in cases where there is an excess of the guppy fry population, as a means of securing their territory and establishing dominance over it.

These are some of the possible reasons why betta fish like to eat guppy fry. It is by no means an exhaustive list but I do think the answers above present a representative enough body of information as to why this phenomenon is so prevalent. Now, as to what as exactly to do about it, here’s some information that perhaps can help you in this regard

How Can You Stop Betta From Eating Guppy Fry?

The easiest solution to prevent betta fish from eating guppy fry is to simply separate the two species of fish. You can accomplish this in primarily two ways.

The first way is to establish separate areas of habitation for the two species by erecting barriers (walls, screens etc.) that prevent one species from gaining access to the other. Most people who use this method like to use a transparent glass screen so that the two species of fish can still see each other but can’t get into to the other species area of habitation. Glass screens are relatively inexpensive and easy to apply and maintain.

The best method of preventing your betta from eating your guppy is to separate them from each other entirely. This means establishing separate fish tanks and keeping the betta in one and the guppies in the other. This solution does require a bit more money for the initial setup and time for the maintenance, but it’s the only solution that’s definitely guaranteed to work 100%.

If you just want to provide the guppies some protection and don’t mind if a few get bullied or eaten, you can just add plenty of hiding places to your aquarium – such as decorations or java moss. If you go this route, you’re going to want a pretty big tank to keep them in. At least a 20 long or larger, to make sure there is enough space that the betta doesn’t feel crowded and try to lash out.


A love of all marine life will makes most of us who own a  mini aquarium to want to have as many species of fish in our tanks as we can. We have to keep this desire in check, however, to ensure that we don’t mix two species together that are just going to kill each other once our back is turned.

Betta fish and guppy fry are two of these incompatible fish species. For the latter this incompatibility is often fatal – something that can be a source of concern and worry for many aquarium owners. 

So, to ensure that this doesn’t become a recurring problem, take care to understand the reasons why betta eat guppy fry and the possible measures to ensure that it doesn’t happen again.