Do Betta Fish Eat Other Fish?

When it comes to fish, everyone knows that they don’t all work together. For example, keeping a goldfish, Oscar, or Flowerhorn with small fish like rasboras will not work. The larger fish will swallow their smaller companions whole. Even though bettas are small, is there a chance that they will eat their tank mates?

The answer to this question is both yes and no. Betta fish have unique personalities, and some are very laid back while others are extremely aggressive. It is unlikely that betta fish will swallow their tank mates whole, but they may take bites out of their tank mates. However, if there are fry in the tank, the betta will likely eat them.

In this article, we will cover aggression, fry, natural diet, teeth, and fins.

Aggression

Some bettas are very peaceful in nature while others will attack anything that moves. Betta fish are territorial fish, since having the best territory often leads to them being able to spawn. Once they pick their area or are forced into one, they will defend it.

Some will understand that their tank mates are non-aggressive and aren’t fighting for their territory and they will leave them alone. Others will see every tank mate as an aggressor fighting for their prime spot.

Betta fish may act peacefully to their tank mates, but when feeding time comes around, they could become aggressive. Food, territory, and mates are the three things that make bettas the most aggressive because those things are worth fighting for.

Due to this, they will first flare at their tank mates, but since most species don’t flare, it is unlikely that the tank mates will understand what flaring means. Instead, the betta will probably resort to attacking their tank mates.

There are ways to “test” your betta to see how it will react to tank mates, but these tests are not certain. You can add a snail to your bettas tank and see how it reacts. This does not give an accurate response for other fish, as snails are slower and able to hide in their shells.

If your betta completely ignores the snail, this is a good sign. On the other hand, if it constantly follows the snail around and bites at it, it is not such a good sign. However, the betta may give up the chase after a few hours to a few days, which means tank mates are possible.

Fry

Some baby fish, also called fry, may be able to fit into the mouth of a betta and be swallowed whole. However, it is unlikely that the domesticated, long finned betta will be able to chase down all the fry in a tank. If the tank has hiding areas for the fry, most will live.

Even though bettas with long fins are slowed down, Plakats and wild bettas are not. A Plakat betta would be more than able to take care of a great deal of fry. Plakats have short fins, so they will be able to chase down fry without the interference of their fins.

On the other hand, wild bettas often do not actively hunt them down. Therefore, fry have a relatively good chance of survival with wild bettas, but a much smaller chance with domesticated ones.

Simply because the domesticated bettas are so aggressive and opportunistic, they will snap at and hunt down passing fry. Some people use bettas as population control for excess fry. Fry are the only fish that are in danger of being eaten by a betta.

If you want to keep betta fish with fry, you should take several precautions. Firstly, add decorations or plants that have thin leaves that fry can hide in. Red root floaters, Anacharis, guppy grass, and hornwort are great plants for fry to hide in.

The betta will not be able to get into such closed spaces, and if you have enough plants, the fry will be able to hide until they are larger. Secondly, pick either a wild betta, such as smaragdina or imbellis, or a long-finned betta.

Natural Diet

Bettas are naturally carnivores, but they prey primarily upon insects and insect larvae. This isn’t to say that they wouldn’t take eggs or fish fry if given the chance, but this instance is not common.

Bettas naturally inhabit the upper level of the water, so they are more likely to get along with bottom dwelling fish. They inhabit the higher levels in order to eat any insects that may fall into or land on the water.

Some insects also lay eggs in water. These eggs hatch into wriggling little larvae, which the betta will happily eat. While other fish may be a very small portion of their diet, bettas quite often do not eat other fish.

Keep in mind that betta fish are relatively small fish. The average body length is only a bit over an inch or two, depending on the species. Some can reach larger sizes, but the ancestors of the pet store bettas are smaller.

Due to their small size, their mouths are also very small. They can’t even open their mouths a quarter of an inch, so eating fish is normally not possible. For this reason, their diets primarily consist of smaller insects, since they easily fit in their mouths.

While some small fish fry may be able to fit into the mouth of bettas, wild bettas often do not actively seek out fry. Fish fry are very fast and given that the areas inhabited by wild bettas are dense in vegetation, most are able to seek refuge in plants.

A single glance from a betta will cause the fry to scatter into plants. Most bettas will not chase down fry, as they are often difficult to catch and not worth the few calories they have.

Teeth

When betta fish become overly aggressive, they will first flare at other fish then chase them. After chasing the other fish, which can be overly stressful to them, the betta will begin to bite their tank mates.

Biting is an obvious issue, but even the chasing is a serious issue. Most schooling fish, which are common tank mates for bettas, are prone to stress. Without a very large school, which the average aquarium cannot sustain, they will always be on edge.

If a “predator” continuously chases them, they will become even more stressed. Stress lowers the immune system of fish, and since these fish are already prone to stress, excess stress can easily kill them.

If they do not die directly from the stress, the lowered immune system is still a major issue. For example, they may contract bacterial infections that can be passed to other fish in the tank.

In addition to the chasing, the biting will leave open wounds. These open wounds can easily become infected with bacteria and even fungus. Fungal “infections” are rare in aquariums, as they can only set in on dead flesh.

Stress plus open wounds is a recipe for disaster. While the betta may not directly eat the fish, at least not whole, their biting can still cause fish death.

Fins

Similar to biting, bettas will also target the fins of other fish. In the wild, betta fish target the sides and fins of other fish in order to tarnish their look. Female bettas are much less likely to mate with a male who has tattered fins.

Open wounds on fins can easily lead to fin rot, which can rapidly spread to other fish in the tank. Bettas themselves are prone to fin rot, so their aggressive behavior can come back to bite them. Even though fin rot is treatable, it is best to avoid the whole incident.

In conclusion, betta fish will only eat other fish if they are fry. Even then, it is unlikely that they will wipe out a whole batch of fry. Despite the fact that bettas will not eat their tank mates, they can still bite, chase, and harass them to death, so care must be taken.