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Do Betta Fish Eat Their Own Eggs? (With Prevention Tips)

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I have caught my betta fish grabbing their eggs into their mouths more than once. I knew that this is how male bettas transfer them into the bubble nest. But I wasn’t sure if some of the eggs were actually being eaten. Fortunately, over the years, I gained experience in this field.

Betta fish occasionally eat their eggs. That typically happens when the eggs are not appropriately fertilized or when too many are laid. However, stressful conditions may compel bettas into eating viable eggs, with the male in particular.

As we move forward, I will elaborate under which circumstances betta fish are likely to eat their own eggs. Then, I’ll discuss whether it’s a good thing and what steps you can take to prevent them from eating viable eggs.

Still curious? Feel free to check my complete guide on betta fish eggs. There, I discussed how to care for betta eggs, what they look like, how long it takes for them to hatch, what equipment to use, and much more.

Do Betta Fish Eat Their Own Eggs?

Yes, they do. Filial cannibalism is relatively common among animals. Hope Klug and Michael Bonsall from the University of Oxford performed a study to identify the factors responsible for filial cannibalism.[1]

They blamed the phenomenon on the parent’s desire to increase their reproductive rate. They also realized that some animals use cannibalism to eliminate inferior offspring. 

However, they admitted that their findings encouraged them to speculate instead of providing factual information. 

Martin Vallon and Katja Heubel (Tubingen’s Institute of Evolution and Ecology) investigated the motivations that compelled fish to eat their eggs.[2]

They realized that fish would prioritize younger eggs as food while steering clear of eggs in the later stages of development. They investigated common Goby and found that the male was responsible for looking after the eggs.

And even though he performed his role adequately in most cases, he also ate some of the eggs. Heubel and Vallon concluded that male Gobies had little or no control over their cannibalistic actions.

This study appeals to aquarists with betta fish because Heubel and Vallon’s observations mirror betta fish behavior. If cannibalism in a betta fish breeding tank concerns you, this is what you should know:

1. The Female Betta Fish

The female betta is a problem. When male and female bettas breed, the father wraps his body around the mother to squeeze the eggs out of her belly. This is one of the first steps he takes to fertilize the eggs.

The process will probably stun the female betta. But once she recovers, you have to remove her. Otherwise, she will snack on the eggs she just laid.

She has no maternal instincts. Additionally, you can’t trust the mother around the hatched fry. She won’t hesitate to eat them.

2. The Male Betta Fish

The betta male is fascinating because he cares for the eggs. Unlike the mother, he will keep them safe until they hatch. The father performs this task by creating a bubble nest at the surface.

The male betta hides the eggs in the bubble nest where they have sufficient oxygen. Some eggs will occasionally fall out. But you can trust the father to retrieve them.

But the male betta’s diligence doesn’t make him harmless. You have to remove him from the tank once the eggs hatch because he may eat the fry.

Every so often, you may also catch him snacking on the eggs. This isn’t necessarily a cause for concern. First of all, bettas generate an average of 30 to 40 eggs every few weeks. So even if the male betta eats some eggs, the female will make more.

Secondly, the male betta is responsible for keeping the unhatched eggs safe. In many cases, that means eating the eggs it did not fertilize. The male betta is capable of distinguishing between fertilized and unfertilized eggs.

Unfertilized eggs are a danger. They will grow fungi that can spread to the healthy eggs, or they will add toxins to the tank when they rot. Therefore, you want the father to eat them. 

But what if the male betta is eating the healthy eggs as well? Well, this can also happen. You can blame such incidents on several causes, including:

  • Personality

Some male bettas are just as bad as the females. They don’t have a paternal instinct. They will continue to eat their offspring no matter what you do. 

You can never predict the personalities your bettas will develop, regardless of whether you bought them from a store or if they grew up in your home aquarium.

You can condition some male bettas, discouraging their cannibalistic tendencies in a breeding aquarium. But if a betta refuses to behave, your only option is to get a new mate for the female.

  • Experience

Some male bettas are simply inexperienced. They don’t understand the role nature expects them to play. As such, they will eat their offspring, but only at the start. Given enough time, they will get the hang of things.[3]

You won’t know whether a male betta is inexperienced or simply bad-tempered until you’ve given him a few chances to care for his children. If the aggression persists, you can write him off.

But if the mating pair lives in a community tank, the adult bettas are also a threat to the eggs. This is also true for any other species in the tank. Fish will eat whatever they can fit in their mouths.

  • Food

Some male bettas can go without food for the two to three days it takes the eggs to hatch. Nevertheless, the hunger may drive others to satisfy their cravings by eating the eggs.

Many professional aquarists are hesitant to feed the male betta because the food may distract the creature. The father might abandon his post to chase the food. 

And once he eats all the food, he may turn his attention to the eggs. Fish have a bottomless appetite. They will continue to eat if you keep feeding them.

The only way to avoid overfeeding is to limit the amount of food you add to their water. But if you have eggs in the aquarium, the father may jump from the food you added to the eggs.

This is another factor that discourages consumers from feeding the male bettas during this period. They don’t want to tempt the fish.

  • Stress

Stress is bad for fish, as betta fish are already aggressive. There’s a reason why people call them fighting fish.[4]

Stress will simply add fuel to the fire. A stressed betta will attack any vulnerable creatures in the water, including unhatched eggs and hatched fry.

You can induce stress in male bettas by performing massive water changes, failing to change the water, and allowing the ammonia concentration to spike.

You may also do this by permitting the temperature and pH to fluctuate, introducing aggressive neighbors, removing the plants and decorations, leaving the artificial lights on 24/7, etc.

3. Mouthbrooder Betta Fish

Mouthbrooder bettas are unique because they don’t blow bubbles. Instead, they keep eggs in their mouths until they hatch.[5]

The strategy is appealing because the eggs are always safe. However, the mouthbrooder is less likely to eat at this stage.

Although, some mouthbrooders will hold the eggs at the bottom of the mouth, leaving room for food. Some aquarists have encountered instances where stress caused a mouthbrooder betta to swallow some of the eggs.

How Do I Keep Betta Fish From Eating Their Eggs?

As I hinted earlier, you should distinguish between female and male betta fish, as each one has its personality and particular role in the breeding process.

For starters, I suggest removing the female as soon as she has done secreting the eggs. She is more likely to eat the eggs and doesn’t play a significant role in caring for them.

Male bettas can eat the eggs as well, as I previously noted. But they are too vital to the general survival of the batch. So, even though they occasionally eat them, I suggest keeping them in the tank until the eggs hatch.

You can remove the male betta fish as soon as the first egg hatches. At this point, the father’s contribution is minimal, and he will gladly eat any fry he encounters.

I also suggest that you cut the meals by half during the days the father takes care of the eggs. It shouldn’t fast entirely, although it is best not to tempt him by feeding too much.

It is also essential to create a stress-free environment. You can easily do that by adding a few decorations and plants. That will build the betta’s confidence.

I also recommend sticking to these water parameters:

  • Temperature: 78-80° F (25-27° C) 
  • pH: 7.0-7.2 
  • Hardness: 5-20 DH (70-300 ppm) 
  • Ammonia: 0 ppm 
  • Nitrties: 0 ppm 
  • Nitrates: <20 ppm

To measure the pH, ammonia, nitrates, and nitrties, I personally use the API FRESHWATER MASTER TEST KIT (link to Amazon). This bundle is a bit more expensive than average. But it lasts for eight hundred measures, so it is pretty cost-effective.

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Conclusions

Fish will eat whatever fits in their mouths, including their eggs. That rule also applies to betta fish. However, male bettas also take care of the eggs. So it may come as a surprise that some even eat their eggs.

But stressful conditions will compel them into doing so. That includes fluctuating temperatures and pH levels, starvation, and the lack of hiding spots.

But if your betta fish merely ate a few eggs, there is nothing to be worried about. Male bettas can identify unfertilized eggs, and they will prefer eating those. That is actually a good thing, as rotten eggs will ruin the water chemistry.

References

  1. https://www.nbcnews.com/id/wbna21790572
  2. https://www.sciencedaily.com/releases/2016/02/160210111907.htm
  3. http://bettafishaquarium.com/do-betta-fish-eat-their-babies/
  4. https://www.thesprucepets.com/why-do-betta-fish-fight-5183979
  5. https://aquariumsphere.com/how-to-protect-fish-eggs-in-aquarium/