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How To Tell If Betta Eggs Are Fertilized!

Due to betta fish being such a popular fish species to keep as pets and female bettas tending to be preferred due to their lower levels of aggression while also usually doing great in a female betta sorority tank, we have noticed more and more questions being asked about female betta fish eggs.

One of the more common ones that we have noticed people asking about recently is how to tell if betta eggs are fertilized?

This is a surprisingly common question that is often surrounded in confusion, especially by people who are brand new to fish keeping as they don’t realize that a female betta fish will still release her eggs even if a male betta is not in her tank.

This then results in people asking if their betta fish was pregnant before they purchased her or why she would release her eggs amongst other things.

We have tried to collect as many of the commonly asked questions that we see from the community about betta fish eggs that we see people asking about to answer in this article.

Our table of contents below allows you to quickly and easily navigate the article and get to specific sections as quicky as possible if you only need answers to a single question. If you are brand new to keeping betta fish then it may be a good idea to read the whole article though.

What Do Betta Eggs Look Like?

Betta eggs tend to be small ovals that are around 1mm in circumference with the eggs usually being any color ranging from transparent to yellow.

Betta eggs in a bubble nest or in the aquarium water tend to be closer to transparent but betta eggs that are being mouth brooded by the male betta fish tend to slowly turn yellow over time.

If you have your female betta fish in a community tank like a betta sorority set up with other fish species in there too then it can be difficult to specifically identify the eggs as betta fish eggs.

This is due to betta fish eggs, especially unfertilized betta fish eggs usually looking very similar to the eggs of many other types of fish too.

This is why people who are actively trying to breed betta fish will transfer a female who is starting to produce her egg but has not yet released them into a standard 10 gallon breeding tank to spawn. The male betta is usually placed in the tank first with plenty of time for him to build up a bubble nest too.

How To Tell If Betta Eggs Are Fertilized!

You are usually able to tell if betta eggs are fertilized as the tiny embryo in the centre of the egg will be visible. The embryo can range from a light grey to a jet black but it is generally very easy to identify in fertilized betta fish eggs.

The embryo in fertilized betta fish eggs tends to grow at a very rapid pace too. It will be considerably larger within a couple of days of the egg being fertilized so you are able to better identify if the egg is fertilized or not.

Out of a full clutch of betta fish eggs, it can be very common with some eggs to be fertilized and others left un-fertilized, especially if the male betta is young.

This is why you will often be able to see the embryo growing in a number of the betta eggs in your tank and not be able to see it in others.

How Long Do Betta Eggs Take To Hatch?

Betta fish eggs tend to hatch after around three days when water conditions are ideal and the betta fry are then on their own to find food and survive.

It can be common for both parents of the hatched betta fry to eat their own babies too as their parental instincts tend to stop as soon as the fry hatch.

Anyone who is actively trying to breed betta fish really should be using a standard 10 gallon breeding tank for the pairing of the male and female betta fish.

After you have identified the embryo growing in the fertilized betta egg, you should be trying to add a fish fry hatchery for the betta fry to safely hide in from their parents.

Some people will try to use a breeding box rather than a breeding tank but this can reduce the egg yield from the female betta due to the additional stress of being in such a small tank.

You are able to try your female betta in a breeding box if you are trying to breed your betta fish but it does tend to be harder than a breeding tank.

What Happens To Unfertilized Betta Eggs?

The majority of unfertilized betta eggs end up becoming a part of the food chain for the aquarium that they live in. The fish, snails, and shrimp in the tank will eat the eggs be them fertilized or unfertilized with the parents also eating their own unfertilized eggs too.

Any unfertilized eggs that are left in the tank and are not eaten will usually be removed during the cleaning process for your tank.

They are easy to catch with a gravel vacuum that you should be using to clean the substrate in your tank anyway.

Some people do try to remove their unfertilized betta eggs from their aquarium as soon as they see them but this tends to be more effort than it’s worth, especially if you have a sorority tank with multiple female bettas.

Simple letting nature take its course and leaving the eggs to become a part of the food chain in your tank is by far the most common option by other fish keepers.


That brings our article going over how to tell if betta eggs are fertilized or not to an end. The embryo growing the betta fish really does grow at a rapid pace so with you can usually see it with ease after the first 12 hours. After a full 24 hours you should definitely be able to see the embryo and then after that the fry starts to fully develop and get ready to hatch.