7 Ways To Tell If Betta Eggs Are Fertilized

Betta fish are a popular pet due to their beautiful appearance and easy maintenance. You might wonder what happens next if you intend on breeding or have noticed eggs in your betta tank. This article will discuss the characteristics of betta egg fertilization and what happens to unfertilized eggs.

In addition, there will be some interesting facts about what you should do if the eggs don’t hatch and the easiest ways to remove them from your tank. If you’re curious about the fertilization process of betta fish, keep reading to learn more.  

What Do Betta Eggs Look Like?

Betta eggs are white and about 1mm in size, almost like tiny pearls. The eggs are not uniform in shape and look more oval-shaped than round. Eggs are incredibly fragile, and you should handle them. Betta eggs are translucent, so you can easily see through them. 

The National Library of Medicine reports how the male bettas build a bubble nest atop the tank and will stay below, waiting for a female when he is ready to mate.

Females will also inspect the nest to ensure it’s up to their standards and will destroy it if she disapproves. Once the female lays the eggs, the male stays to protect the nest; if any eggs fall out, he will put them back in. 

Once a male creates the bubble nest, it usually triggers the female to mate. While eggs can hatch without a bubble nest, there’s uncertainty about whether they will survive. Instead, the nest gives the eggs a safe, secure resting place until hatching. 

What Do Unfertilized Betta Eggs Look Like?

In the beginning, fertilized and unfertilized eggs look similar; however, unfertilized eggs appear fuzzy and show no signs of growth. After a few days, there will be no change to the eggs, and you will not see a fish start to appear inside. 

In addition, unfertilized eggs stay white, while fertilized eggs begin to change color. Also, no gray spots will start to appear. If you only have a female, your betta eggs are infertile. Therefore, you must have a male and a female to produce fertile eggs. 

It is also possible to have unfertilized eggs if a pair of bettas have never mated. 

How To Tell If Betta Eggs Are Fertilized 

Fertilized eggs, also called fry, have distinguishing characteristics that can help you determine whether they will produce babies or not. For example, a female betta doesn’t necessarily fall “pregnant” because she can lay eggs but requires a male to make them fertile. 

You’ll likely notice a bulging belly from your female and white strips on her side when she is about to lay eggs. When a female is in this state, it’s referred to as a “gravid state,” and the male will extract the eggs shortly.  

A male and female betta are seldom together, so you’ll likely only have fertilized eggs if you purposely want to breed your bettas. Bettas can be territorial and aggressive if left together, so consider your tank situation if you house them with each other. 

If you are still uncertain whether you have fertilized eggs, here is a list of ways to determine the type of eggs in your tank. 

Fertilized Eggs Have a Gray Spot

One of the most distinguishing characteristics of fertilized Betta eggs is they develop a significant gray spot as they grow. Gray spots will be prominently displayed in the egg’s middle, making it easy to spot. Betta eggs can turn black, but they are still fertile. 

Eggs Turn Shades of Yellow and Brown 

The white Betta eggs will soon develop shades of yellow and brown as they grow. As your eggs get closer to hatching, you can see the white yolk sac and a small fish inside. Since hatching time comes quickly, the betta eggs will start turning colors within the first day or two. 

Eggs Show Slight Growth 

While fertilized betta eggs don’t grow immensely, they will develop a little before hatching. However, the growth is so slight that you may not even notice. An unfertilized doesn’t show any change because there is a lack of an embryo. 

Eggs Develop Two Black Dots for Eyes 

Betta eggs are translucent; therefore, you can spot two black dots in the betta’s eyes. In about a day or two, you can see the eyes of the fertilized eggs. 

You Can See An Embryo In Betta Eggs 

You can tell if a betta egg is fertilized by seeing the formation of a tiny embryo inside. The embryo grows fast and will be distinguishable rather quickly. 

Betta Eggs Hatch in Three Days 

Fertilized Betta eggs typically hatch within three days, but it can vary depending on the temperature, water quality, and the species of your betta. For example, a betta macrostoma can take up to a month to hatch.

Warmer temperatures could produce hatching in less than 24 hours, so don’t be surprised if you find fry within a day. Fry can find food within a few days and can survive quickly. 

Male Betta Cares For Eggs 

Males will care for any fertilized eggs and are better caretakers than females. So, once the female lays the eggs, they can be removed, especially since they are prone to eat them if left unattended. 

Males will care for the eggs until they hatch and swim independently.

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What Happens to Unfertilized Betta Eggs?

Male betta often eats unfertilized betta eggs to focus on the fertile ones. Males will also eat damaged eggs and, if stressed, regular ones. But, since males can get stressed quickly, keeping a peaceful and serene environment for your betta is vital. 

The male can stay with the newly hatched fry for a day or two while they feed on the yolk sac. In addition, if you have any other aquatic life in your tank, including shrimp and snails, they will help eat any unfertilized eggs. Letting the food chain do its job is an easy way to remove unfertilized eggs.

Once the fry begins swimming, which will be horizontal, you want to remove the male as he may start eating the babies. 

Also, if a female lays unfertilized eggs without a male present, she will often eat them. You may not even know she laid eggs; she will eat them before you notice. 

What Should I Do If The Eggs Don’t Hatch?

There’s a good chance you will have eggs that don’t hatch, even fertilized ones. Since a female can lay hundreds of eggs simultaneously, the likelihood of unhatched eggs is high.

So if you’ve waited several days for them to hatch to no avail, these steps can help you with proper removal. Remember, sometimes it takes more than one attempt to remove unhatched eggs. 

Remove Eggs From The Tank 

It’s crucial to take action if your eggs don’t hatch because rotting eggs can produce ammonia which can harm fish. You can remove them by vacuuming the bottle of your tank or using a net to pick up individual eggs.

Eggs can get hidden behind rocks and stones, so ensure you thoroughly clean your tank. In addition, it’s vital to clean your tank routinely to prevent bacteria or fungus from growing. 

Let The Male Eat Unhatched Eggs 

As we now know, males will get unfertilized eggs, and sometimes you can leave it up to them to take care of any unhatched eggs. However, you do want to be mindful not to let too much time pass to avoid bacterial growth in your tank.

If the male hasn’t done the job within a week, it’s time to remove them on your own. Keep reading to find helpful ways to remove unhatched eggs from your tank. 

Separate The Male And Female 

If you have eggs that don’t hatch, it’s wise to separate the male and female. The male can take care of the fish that have hatched while you work on removing the other eggs.

Males and females can get aggressive if left together, so separating them will prevent anything from happening to the newly hatched babies. 

Add Predators To Your Tank 

Some predators will eat the eggs for you. But, of course, you want to ensure you remove any live bettas first. Predator fish include Bucktooth Tetras and Jaguar cichlids, which you can find at your local fish store. 

If you add additional fish, remember that you will have to care for them afterward. While predators are beneficial, you can’t stop caring for them once they care for your unhatched eggs. 

Use A Siphon To Remove Unhatched Eggs 

If you have unhatched eggs amongst babies, you want to be careful about how you remove the rotten eggs. You can use a siphon or turkey baster to suck out the unhatched eggs and then carefully dispose of them.

The American Biology Teacher also suggests using an eye dropper to remove unhatched eggs. You’ll want to throw away any utensils you use to remove unhatched eggs. 

Remove Bubble Nest If Necessary 

If it’s been several days and your eggs still haven’t hatched, you may want to remove the bubble nest. The leftover eggs can ruin the pH of your tank, making it hard for your betta to breathe. Therefore, you should also test your water parameters to ensure safe levels.


Do Betta Fish Eggs Need To Be Fertilized?

Betta fish eggs don’t require fertilization. However, they must be fertilized to hatch, meaning both the male and female must be fertile. Therefore, the male is responsible for fertilizing the egg. 

What Color Are Fertilized Betta Eggs?

Fertilized eggs are white with a different gray spot. Most fertilized eggs will develop a brown or yellowish shade before hatching. Betta eggs will also begin to show the growing embryo inside. 

How Many Days Do Betta Fish Eggs Take To Hatch?

Betta fish eggs take three days to hatch, but this can vary based on species and water quality. If it’s been more than three days, your betta eggs are likely infertile, and removing them is best. 


The easiest way to determine if you have fertilized eggs is by their appearance. Fertilized betta is about 1mm in size, white, and oval-shaped. You can tell unfertilized eggs because they may appear fuzzy, won’t grow, and lack distinguishable gray spots.

In addition, fertilized eggs usually hatch within three days and develop two black dots representing their eyes. Male betta fish will eat unfertilized eggs, but you should clean your tank if you see any after several days.