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What Do Betta Fish Eggs Look Like? (With Detailed Pictures)

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I remember how excited I was when I first saw my female betta secreting her eggs. But that also raised many questions. What do betta fish eggs suppose to look like? Is there a difference between fertilized and unfertilized eggs? As the years passed, I gained some knowledge in this field.

Betta fish eggs look like white pearls and are 1mm in diameter. Fertilized eggs grow a bit larger and develop yellowish shades. Eventually, two dots appear, which are the fry’s eyes. On the contrary, unfertilized eggs remain white and don’t change.

As we move forward, I will share some detailed pictures of what betta fish eggs look like. I will show you the differences between fertilized and unfertilized eggs and what you may see at the final stages, just before the fry hatches.

A picture of a female betta fish releasing her 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.

What Do Betta Fish Eggs Look Like?

Female bettas give birth when a male fish squeezes the eggs out of their bodies, a process that exhausts the mother. The father is also responsible for fertilizing the eggs. It does this by releasing milt into the aquarium.[1]

Once the father moves the eggs to the bubble nest, you will notice the following changes:

1. Fertilized Betta Fish Eggs

Betta eggs are tiny (1mm) and white. They look like tiny pearls. Mouthbreeder betta eggs are larger, ranging from 2 to 3mm. But if you’re new to bettas, your fish retailer will probably recommend ordinary betta fish.

It takes betta eggs just three days to hatch. Therefore, they won’t change quite as drastically as eggs from other species that require several days or even weeks to hatch.

In fact, your betta’s eggs may hatch before you even realize that the fish spawned. If you’re paying close attention, you will notice gray spots on the eggs:

The betta fry’s eyes, seen through the eggs’ shell.

Additionally, the eggs, which are more oval than round, will grow in size. The change in size is small but noticeable for observant aquarists.

Within three days, baby bettas will emerge from the eggs. This is the most significant difference between fertilized and unfertilized eggs.

Fertilized eggs change because they have an embryo that continues to mature. That embryo forces the egg’s color to change. While some eggs develop gray spots, others will turn jet black.[2]

Don’t forget: the shell is technically translucent. If you take a closer look, you will see the baby fish as it matures inside the egg. The organism will absorb the light, transforming the egg’s color. In the absence of this embryo, an unfertilized egg remains unchanged.

An image showing living betta fish fry, seen inside and outside the bubbles.

2. Unfertilized Betta Fish Eggs

You don’t have to go through the trouble of differentiating between fertilized and unfertilized eggs. Both types are white and oval at the start.

The fertilized eggs will grow slightly and gradually over the next few hours and days. Also, fertilized eggs will gain yellowish or brownish colors:

This image demonstrates unfertilized betta fish eggs on the left and fertilized eggs on the right.

However, if you’ve failed to notice the gray spots or the difference in size between fertilized betta eggs and their unfertilized counterparts, you can just wait for the fertilized eggs to produce betta fry.

The unfertilized eggs won’t hatch. But some people don’t want to wait for the fertilized eggs to hatch, as they want to identify and eliminate the unfertilized eggs immediately.

Experienced aquarists will encourage you to keep three factors in mind.

  • First of all, finding the unfertilized eggs in a batch of 50 or more betta eggs is easier said than done. The father keeps his offspring in a bubble nest, retrieving every egg that falls out.

You will have a difficult time differentiating between the eggs and bubbles, let alone fertilized and unfertilized eggs.

  • Even if the eggs are out in the open, you don’t have to obsess over the unfertilized eggs. The father will identify and remove them.

Some male bettas will eat healthy eggs because of stress, especially if the conditions in the water are poor. But most fathers are programmed to eat unfertilized eggs while caring for the healthy eggs.

  • Unfertilized eggs are dangerous. They will decompose, introducing toxins like ammonia to the water, which is why aquarists remove them.

But you don’t lose anything by permitting the unfertilized eggs to stay in the water for the first three days. You can afford to wait for the healthy eggs to hatch.

After three days, feel free to remove any unhatched eggs left in the tank. You can assume that they won’t hatch. Unfertilized eggs have a static appearance, as they remain white.[3]

This image shows a male betta fish catching the eggs that the female has just secreted.

But eggs in a bubble nest are challenging because the bubbles refract the light. This creates the illusion of a color change where non exits. In other words, white unfertilized eggs inside a bubble nest may look gray or black.

But again, after three days, fertilized eggs will hatch, adding new bettas to the aquarium. The unfertilized eggs will remain the same.

If you have more unhatched eggs than you expected, they shouldn’t concern you. Bettas can produce as many as 500 eggs. Don’t expect the father to fertilize them all.

The male betta may neglect dozens of eggs during a spawning session, especially if the breeding pair is new and inexperienced. But if you maintain optimal conditions in the tank, the number of healthy, fertilized eggs will increase later on.

This image shows a male betta fish searching for unfertilized eggs that have sunk to the bottom.

3. Eggs Infected With Fungi

Does your tank have unhatched eggs? Well, if it does, they won’t remain white forever. Over time, their shells will become fuzzy as fungal infections take root.[4]

Unfortunately, you can’t avoid fungus. This problem affects both fertilized and unfertilized eggs. Unfertilized eggs with fungal infections stand out because they become opaque.

Translucent eggs with fungal infections are still viable. But they can die if you permit the fungal infection to go unchecked.

Fungus induces panic among aquarists. It is partially responsible for their determination to separate fertilized and unfertilized eggs.

Fungi on unfertilized eggs will eventually jump to the fertilized eggs, compromising their health. You can find fungi in various species, with the most common being Saprolegnia and Achyla.[5]

Once fungi infect healthy eggs, you are better off removing them with forceps and needles. They are unlikely to recover.

But as you probably know, this doesn’t apply to fish. You can treat bettas that develop fungal infections. Don’t be so quick to discard them. The creatures have better defenses against fungi than eggs.

Methylene Blue is common among betta fish enthusiasts. It can prevent fungal infections in betta fish breeding tanks.[6] Potassium permanganate is another popular solution. Though, it is more likely to help fish than eggs.[7]

As with everything, prevention is better than a cure. You can prevent fungi from running wild by keeping the breeding tank clean. Some people add methylene blue to their aquariums the moment a female betta lays its eggs.

The goal is to prevent the fungi from infecting the fry. But you shouldn’t respond to a fungus infestation by adding more methylene blue than the packaging recommends. Otherwise, you may saddle the baby bettas with developmental issues.

Don’t be afraid to eliminate your entire batch of eggs in a tank where you can’t differentiate between fuzzy opaque unfertilized eggs and translucent spotty fertilized eggs.

Sometimes, this is the only solution to heavy fungal infestations. Your bettas will lay more eggs in a few weeks.

This image shows two eggs with a fuzzy appearance, suggesting they were infected with fungus.

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

As previously noted, betta fish eggs take approximately three days to hatch. After that period, they are unlikely to produce offspring. For that reason, it is best to remove the eggs as well as the bubble nest.

If you let the eggs sit a couple of days longer, they may rot and produce ammonia and nitrates. And as toxins increase, your betta will find it harder to breathe.

At a certain point, the pH goes lower, and your betta will be harmed severely. Male bettas can eat unfertilized eggs. However, if hundreds have been laid, the father will find it challenging to eliminate them.

I also suggest that you test the water after three days. Aim for 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

These are optimal for betta fish and ensure they reproduce efficiently. Even if the current batch fails, these conditions make it more likely for the next one to succeed. 

To measure the pH, ammonia, nitrates, and nitrties, I personally use the API FRESHWATER MASTER TEST KIT (link to Amazon). After trying dozens of kits, this one is probably the most accurate and cost-effective.

I also recommend getting the well-known Kordon Methylene Blue (link to Amazon). Besides preventing fungal infections, this product is also effective against parasitic conditions, such as Ich, Chilodonella, and Costia.

For the curious among you, here is a detailed Youtube video that illustrates the development of fertilized betta fish eggs:

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Conclusions

In the first two days, betta fish eggs will look like pearls, round and entirely white. Fertilized eggs will grow slightly, and their diameter will be just over 1mm. They will also become yellowish and develop two black dots resembling the fry’s eyes.

Unfertilized eggs don’t change at all and remain white. After a few days, you may see a cotton-like coat surrounding the egg. That is most likely a fungal infection, which indicates that the eggs should be removed.

References

  1. https://en.wikipedia.org/wiki/Siamese_fighting_fish
  2. https://pawfectpawprint.com/how-to-tell-if-betta-eggs-are-fertilized/
  3. https://badmanstropicalfish.com/how-to-tell-if-betta-eggs-are-fertilized/
  4. https://lifeoffish.com/how-to-tell-if-betta-eggs-are-fertilized-12-unheard-facts/
  5. https://www.petcoach.co/article/common-aquarium-fish-fungal-infections-causes-and-treatment/
  6. https://lovemybetta.com/betta-fungal-infection/
  7. https://www.petmd.com/fish/conditions/skin/c_fi_saprolegnia