Why Are My Betta Fry Dying? (With 5 Practical Solutions)

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Betta fry are fairly delicate creatures that can quickly die when handled inappropriately. I used to lose large batches in the past, and it took me quite some time to learn what I was doing wrong.

Betta fry typically die for the following reasons:

  1. The water conditions are not adjusted for betta fry.
  2. There are elevated toxins in the water, like ammonia and nitrate.
  3. The water changes are done wrong.
  4. The fry were overfed or underfed.
  5. The tank is not cycled.

As we move forward, I will elaborate on why your betta fry are dying. After that, in the second part of this article, I will show you what steps you should take to prevent this from happening.

Two months old female betta fry, living together peacefully.

Still curious? Feel free to check my complete guide on betta fish fry, where I discussed how to care for betta fry, what they eat, their growth stages, what equipment to use, and much more.

Why Are My Betta Fry Dying?

Betta offspring are delicate, which is basically true for every young fish. You cannot expect the male bettas to fertilize every egg the female produces. 

Some eggs will rot. And even among the eggs that hatch, you cannot expect all the fry to survive. Some of them will die, and this shouldn’t concern you. 

However, as I previously discussed, 90 percent of the betta fry are expected to survive when taking the proper measures.

So what if you’re losing more betta fry than usual? What if you keep losing entire batches of fry before they reach adulthood? You can blame one or more of the following factors:

1. The Water Conditions Are Bad For Betta Fry

This has to be your first consideration. If you’re losing baby bettas in large numbers, the conditions in the breeding tank have deteriorated. 

Adult bettas are hardy, as they can tolerate poor-quality water for a while. But betta fry are not that strong. They need a conducive and stress-free environment to mature into healthy adults. 

Harsh conditions will either kill them or expose the creatures to diseases that can lead to death. That includes the following:

  • Small tanks are dangerous because they create crowded conditions, and unfortunately, crowded conditions attract stress and diseases. The ammonia concentration is more likely to increase.
  • Do you have a filter? The absence of a decent filter can also encourage the ammonia concentration to spike. Filters remove pollutants like leftovers from the water before they can rot.

The absence of a decent filter will also affect the oxygen levels in the aquarium. Don’t forget: oxygen enters the tank at the surface. 

You can improve the circulation of oxygen by agitating the water. Without a functional filter, the water will stagnate, and the resulting oxygen deficiency will kill the fry.

It isn’t enough to maintain the appropriate parameters. If you allow the temperature and pH to fluctuate, the drastic changes will harm the fry. 

Adult fry can withstand fluctuations, but the fry are still too young and sensitive to survive in a tank where the parameters keep shifting. 

2. There Are Toxins In The Water

Ammonia and nitrate levels of more than 25ppm and 0.25ppm, respectively, can kill all the fish in an aquarium. The best response to ammonia is to change the water.

But a water change can make things worse if you forget to purify the new water. For instance, tap water will introduce chlorine and chloramine to the aquarium.

Two days old betta fish fry, recently detached from his bubble.

3. Inappropriate Water Changes

Water changes are tricky. On the one hand, you cannot keep baby bettas alive without changing the water. They are a vital component of your aquarium’s maintenance routine.

On the other hand, significant water changes will kill the betta fry. A large water change will produce the kinds of fluctuations they hate. 

People resort to significant water changes because they have detected dangerous ammonia spikes, and a drastic water change can bring relief to adult bettas in a tank saturated with toxins.

But betta fry are too sensitive to tolerate significant water changes. By trying to help the baby bettas, you will kill them. 

4. Overfeeding And Underfeeding

Overfeeding and underfeeding is common in breeding tanks. Some people underfeed their betta fry because they want to avoid overfeeding. 

They don’t realize that baby bettas have voracious appetites. You have to feed them several times a day to maintain their health.

Others overfeed the betta fry. Overfeeding is not a significant problem if you have a decent filter and a strict maintenance routine. 

But if you have a negligent attitude towards your fish, overfeeding will destroy the aquarium’s equilibrium by choking the water with rotting waste and leftovers.

A male betta fish, taking care of his newborn fry.

How Do I Keep My Betta Fry From Dying?

Even though betta fry are sensitive, you can keep your entire batch alive if you take the following precautions:

1. Make Sure Your Tank Is Cycled

Is your tank cycled? The Department of Animal Nutrition, Genetics, Production and Ethology, Ghent University, published a paper that emphasized the importance of creating a nitrogen cycle in the water.[1]

A nitrogen cycle creates bacteria that process fish waste and leftovers. It turns ammonia into nitrites and nitrates, which are not as toxic.

You have to cycle the tank to completion to prevent persistent ammonia spikes. The process is surprisingly long and can easily last 4 to 6 weeks.[2]

But you can expedite it if you acquire filter media from an established tank. You cannot control the ammonia concentration in an uncycled tank.

Another way to cycle the tank pretty fast is to use the well-known API QUICK START (link to Amazon), which contains nitrifying bacteria.

Two tablespoons for every 10 gallons of water will do the trick. You can also use this product when adding new fish to your tank or replacing the filter’s media.

2. Adjust The Water Conditions For Betta Fry

Cycling is the most critical consideration. You cannot keep betta fry alive in an uncycled tank. But if you cycled the tank to competition and the fish are still dying, buy some kits and test the pH and temperature.

Aim for these water parameters when it comes to betta fry:

  • Temperature: 85-88° F (29-31° C) 
  • pH: 7.0-7.2 
  • General hardness: 2-20 dGH (70-300 ppm) 
  • Carbonate hardness: 3-5 dKH (55- 90 ppm) 
  • Ammonia: 0 ppm 
  • Nitrites: 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 one is highly accurate and lasts for hundreds of measures.

As for the water hardness, you can simply go with the API GH & KH TEST KIT (link to Amazon). But frankly, almost every kit on the market will get it done.

As far as the tank size is concerned, you should aim for 5 gallons.[3] Bigger tanks are easier to maintain. But the aquarium shouldn’t be so large that the betta fry are at risk of starving because they cannot cross the tank to find food.

  • An article in the International Journal of Development Research (Effect of Environmental Enrichment On The Behavior of Betta Fish Exposed to Incident Sunlight) highlighted the vital role sunlight plays in a fish’s development.[4]
  • Apparently, UV rays stimulate the production of Vitamin D. 

But if you’re hesitant to expose your aquarium to direct sunlight because you don’t want the algae to grow out of control, the IJDR article found that aquarists could replicate the benefits of direct sunlight by installing artificial lighting.

Either way, do not expose your fry to too much light. I personally suggest creating a proper day/night cycle by turning the lights on for a maximum of 10 to 12 hours.

Newborn betta fish fry, still hanging to their bubble nest.

3. Conduct Proper Water Changes

Keep the water changes to 25 percent. You can change the water twice a week to prevent the ammonia concentration from running amok.

You can also change the water every day if you want. But you should bring the volume down to 5 percent. The goal is to keep the water clean while minimizing the fluctuations.

Don’t forget to apply conditioners to the new water. You can use conditioners to neutralize toxins like ammonia and chlorine.

4. Make Sure There Is Enough Oxygen

A breeding tank doesn’t require air stones or pumps. If you have a decent filter, it will generate enough agitation to keep the water sufficiently oxygenated. 

But if you tested the water and the oxygen levels are lower than expected, you can add some air stones.

You can check the oxygen levels using a dissolved oxygen meter or a chemical test kit, such as the Monitor DISSOLVED Oxygen Test KIT link to Amazon).[5]

Better yet, observe the fry. Common symptoms of oxygen deficiency include lethargy, erratic swimming, and loss of appetite.

5. Feed Your Betta Fry Properly

What your betta fry eat will most likely determine their growth rate. But feeding betta fry can be tricky, as they eat different kinds of food at different stages.

Here is a table that gathers what you should feed them depending on their age:

InfusoriaUntil they reach day 7
Baby brine shrimpFrom day 7 to 21
Freeze-dried/frozen foodsFrom day 21 and beyond
BlackwormsFrom week five and beyond
Dry pelletsFrom week eight and beyond

Give the betta fry 4 to 5 meals a day. As a rule of thumb, I suggest prioritizing live foods like brine shrimp, bloodworms, and grindal worms.

After a month, your betta fry will enter their ‘Young’ stage. At this point, you can cut down the meals to three times a day. At the age of 3 months, you can feed them like adults.

If you found this article helpful, these may also interest you:

Pro tip: If your betta fish breed frequently, you probably need to know a little about their eggs. You can find my complete guide on that topic here.


If your betta fry die in large batches, something is done wrong. Unlike other types of fish, most of the betta fry should survive when dealt right, approximately 90 percent.

If this happens to you, the first step would be to buy a water test kit. Measure the pH, ammonia, nitrates, and nitrites, and make sure they fall within the desired range.

If your tank is new, it could be that it hasn’t cycled yet. You can quickly fix that with commercial nitrifying bacteria. At last, make sure you feed your fry properly while considering their age.


  1. https://core.ac.uk/download/pdf/153396734.pdf
  2. https://www.thesprucepets.com/seeding-new-aquarium-1381286
  3. https://pethelpful.com/fish-aquariums/Reasons-Betta-Fish-Die
  4. https://www.journalijdr.com/sites/default/files/issue-pdf/18890.pdf
  5. https://aquariumsavvy.com/how-do-i-check-the-oxygen-level-in-my-fish-tank/