Fertilized Betta eggs in an aquarium are small, oval-shaped, white-colored balls. Everything from fertilization to raring is the responsibility of the male Betta, but the laying of the eggs is up to the female Betta.

In our article below, we will be outlining the ways in which you can tell that betta eggs are fertilized, the time it takes for the eggs to hatch, as well as the mating and laying-the-eggs processes. Read on to find all of this valuable information!

How to Tell If Betta Eggs Are Fertilized?

Fertilized fish eggs grow larger day by day and have a prominent gray spot in their center, indicating their fertilization. It’s also worth noting that the newborn bettas that will pop out of the fertilized eggs are often referred to as fry. On the other hand, unfertilized fish eggs will be completely white, and if you notice them for a period of days, you would see they have turned fuzzy and are not growing. Moreover, you won’t see any grey spots in unfertilized eggs.

If you have mouth-brooding Betta fish, their eggs would be slightly larger than the regular Betta eggs and take longer than the average time to hatch. Unlike the normal male Betta fish, mouth-brooding males keep the eggs in their mouths until the fry is released. On emerging, they acquire a yellow color which gradually darkens.

How Are Betta Eggs Fertilized?

The male Betta fish fertilizes an egg as soon as it comes out of the female Betta’s egg hole. A female Next, the male Betta fish fertilizes the eggs after the female has laid them. The male Betta creates milt and keeps the eggs there until they hatch and is its responsibility to provide for them and keep them safe in that nest.

Notably, Betta fish can lay 30 to 40 eggs in one go, and in some rare cases, they can even produce up to 500 eggs.

However, to have fertilized eggs, you need to have fertile parents. But, it is not necessary for every egg in the aquarium to be fertilized. Sometimes, even if parents are fertile but have no mating experience, they can produce unfertilized eggs.

– Stress Eating Fertilized Eggs?

Since the male betta fish is concerned about fertilized eggs only, it often consumes the unfertilized and damaged eggs. However, in some exceptional cases, Betta fish are also seen eating the fertilized eggs. That could be stress eating, so try to keep your fish in a relaxed and peaceful environment to avoid this situation from happening.

– The Necessity of Male Betta Milt

The male Betta fish is not necessary for the production of Betta eggs. That’s because it seldom happens that the male and female fish are together in an aquarium. You can verify it by putting your Betta fish in a separate aquarium.

This way, you will understand the following loophole: the female fish would lay eggs and they’d in perfect condition, but they won’t survive because the female Betta fish would eat them.

That is why male Bettas are required. As soon as the egg comes out of the egg hole, the male Betta creates a bubble nest for the potential fries. This bubble is called milt and helps fertilize the Betta eggs.

How Long Does It Take for The Betta Eggs to Hatch?

Regular Betta fish eggs hatching can take up to two or three days or, depending upon a number of factors. There’s a chance that it may take longer than that.

For example, the mouthbrooder Betta fish needs an extended period to hatch. It can take about a week or two or sometimes up to a month.

– What Happens After Hatching?

The Betta fries don’t become independent right after being released. For the next day or two, they feed on the yolk sack, and if they fall out of the Betta nest with eggs, their father is responsible for handling them and putting them back where they belong.

After another day or two, the fry starts growing, learns to swim, and stops depending on its father.

Properly Breeding and Hatching of Betta Eggs

Below are some crucial factors necessary for the proper breeding and hatching of Betta eggs:

– Temperature

Since Betta eggs are to develop and hatch in the water, the temperature and environment must be per their preference. At high temperatures, the digestion rate and metabolism of Betta fishes increase, and that directly affects their growth. Eggs growing in the 75 F range will grow in more or less 24 hours, whereas the same eggs kept at a lower temperature can require up to three days to hatch.

A recent study has proven that the higher the temperature, the faster the fry develops, and the lower the temperature, the more time it takes. The eggs grow relatively faster at 86 to 93 F with some issues in hatching and survival, but 78.8 to 82 F is quite the optimal temperature with fewer risk factors.

This temperature is for Betta eggs only, though; adult fish might be victims to a reduced life span if they keep living in warm water.

– Water Quality

The water quality of your aquarium directly influences the growth rate and health of the Betta eggs. Betta eggs breeding in dirty water could cause some, or in extreme cases, all of your eggs to become hollow or die. Although having Betta eggs on the bottom of the tank is unusual but if their water is dirty above a tolerable level, they would sink to the bottom and that is not a good sign.

If you haven’t cleaned the water in the fish tank or don’t have a filter installed, you might have a gunk buildup. The poop of the fish in the aquarium could result in the rise of ammonia levels which are deadly for the fish. Besides the ammonia buildup, the usual dust and harmful substances from the air mix up in the water and create an unclean environment as well.

Initially, when the female Betta lays eggs, the water needs to be clean, since at that stage, the female fish and Betta eggs are all vulnerable and can catch germs in the blink of an eye. Fortunately, this happens seldom and isn’t something you need to fret about too much.

After How Much Time Can a Female Fish Lay Eggs?

Female Betta fish is one of the most productive fishes usually kept as pets. They lay eggs every two weeks, so your aquarium would be overflowing with fries in a couple of months only. However, the period may vary from fish to fish.

This means that if your fish seems a little worn out or has grown old, it might need more time to strengthen up before laying more eggs. Similarly, the male Betta fish needs to be healthy enough to fertilize and protect the eggs.

When is the Female Betta Fish Ready to Mate?

When the female fish is ready to mate, the colors on its skin will turn a darker tone indicating that it’s ready to mate. Also, during this period, you would be able to observe a barring pattern on its skin that is developed when the female is ready to mate.

Right beside her mid area, there would be a vertical stripe indicating fertility. And if you see the egg hole of the fish open more often than usual, know that it’s another sign that the female fish is fertile and ready to mate.

Things to Consider

Before you decide to breed your Betta fish, you need to be mindful of a couple of things. These are:

  • Purchase your Betta fish from a well-known breeder, so you receive all the adequate information about it.
  • If you have both the female and male genders, initially keep them in different tanks.
  • Place the aquarium in a secluded area, so the fish have privacy and feel safe.
  • If the male Betta behaves aggressively before the mating starts, separate it from the female Betta.
  • In the case that fertilized eggs are laid, move the female fish out, keep the fries with the male Betta and wrap some plastic over the aquarium to speed up the hatching process.


We’ve covered plenty of information on how to tell if Betta eggs are fertilized. Let’s sum everything up so you can have all the facts in a compact form:

  • If the eggs are white with a grey dot in the middle and grow gradually, know for a fact that they are fertilized
  • The female Betta fish can lay eggs without the help of the male fish
  • The male Betta is responsible for fertilizing the eggs and protecting them
  • The eggs can take up to one to three days to hatch
  • A female fish can lay eggs every two weeks of the previous laying
  • When a female fish changes its colors, it indicates it’s ready for mating

Now that you have gone through our article, you have all the vital information you need to spot the fertilized eggs from the unfertilized ones, as well as anything else with regards to the Betta eggs fertilizing and hatching process!

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