How Many Days do Cory Eggs Take to Hatch?

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Corydoras are eager to breed in captivity, although they require specific conditions to reproduce successfully. Fortunately, these aren’t difficult to achieve, provided you know what the fish needs.

Today, we will discuss a particular aspect of breeding cory catfish that isn’t discussed much in the aquarium trade. I’m talking about egg care and maintenance.

How Many Days do Cory Eggs Take to Hatch?

Corydoras eggs take approximately 3 to 6-7 days to hatch. The hatching period depends on several criteria, including water parameters like temperature and environmental cleanliness.

Dirty waters increase the risk of fungal infections, which will render the eggs useless, for instance.

As a general rule, you should boost the water temperature a bit during the incubation period to speed up the process. We’ll discuss this aspect shortly.

Do Cory Eggs Hatch On Their Own?

Yes, they do. Corydoras eggs don’t need any special attention from the fish or you, for that matter.

So long as the water conditions are adequate, the eggs will develop and hatch when the time is right. Since we’re discussing water conditions, keep in mind that the sooner the eggs hatch, the lower the chances of fungal infections.

So, your goal should always be to lower the incubation period as much as possible. To achieve this, consider increasing the tank’s temperature to 78 F, which is slightly more than the typical 75-76 F that adults require.

The warmer waters will incentivize the embryo to grow faster, lowering the incubation period dramatically.

A similar temperature in the neighborhood of 76-78 F should be maintained in the nursing tank to speed up the fry’s growth.

The higher temperatures will aid with digestion and speed up the fry’s metabolic rates, allowing them to grow faster and larger.

Also, keep water currents minimal to prevent the water from moving the eggs all over the place.

How to Tell if Cory Eggs are Fertile or Not?

You have a way of distinguishing between fertile and infertile eggs, and that’s the color. All eggs are white at first, but they turn darker when fertilized.

Infertile eggs remain pasty white, which is a sign that they will soon become food for bacteria and fungus.

You can tell that the eggs are disposable past the 24-hour mark. If they haven’t been fertilized by that point, there’s no reason to wait anymore.

You should remove infertile eggs from the environment to prevent fungal or bacterial growths that can also spread to the fertile eggs.

How do You Care for Cory Eggs?

You want to separate the cory eggs and the adult fish because Corydoras aren’t exactly popular for their parental instincts.

The overwhelming majority of Corydoras don’t care about their eggs or fry upon hatching. They won’t hesitate to eat them if they run into them by chance.

Your best approach begins with investing in a breeding or nursing tank. I recommend both for obvious reasons.

The idea is to either separate the eggs from the general fish population or have the Corydoras pair breed into a different environment altogether. You can then remove the fish to protect the eggs.

Then you set up the ideal tank parameters and begin the waiting game. The eggs don’t require any assistance to incubate properly, so long as temperature and water quality are ideal.

Should You Move Cory Eggs to Other Tank?

Yes, I think you should.

Granted, you can keep the eggs in the main tank if:

  • You have a cory-only aquarium with no other fish species present
  • You don’t have snails or shrimps that could eat the eggs
  • You have plenty of plants, rocks, and substrate decorations that could protect the eggs
  • Your Corydoras are well-fed, so they’re unlikely to eat the eggs

I would advise ignoring the latter point, though, because it’s unlikely to deliver the expected results.

Corydoras are scavengers by nature, so they won’t stop looking for food near the substrate, no matter how well-fed they are.

A nutritious and well-balanced diet will make them less interested in eating their eggs in case they find them, but it won’t stop them completely.

If you’re not interested in keeping all your Corydoras eggs, keeping them in the main tank should do it.

Not all will hatch, but some will. If, however, you want to keep as many fry as possible, you need to invest in a breeding tank.

How do You Remove Cory Eggs from Glass?

It’s often the case that Corydoras lay their eggs on the tank glass. The eggs are sticky, which secures them against faster-moving waters.

But how do you remove them from the glass without destroying them in the process?

Fortunately, this isn’t too difficult to achieve. You can simply use your fingers or a metal or plastic blade or any similar tool to that effect.

The eggs shouldn’t be too difficult to remove, but be careful about relocating them. You can easily crush them if you don’t handle them with care.

Pro tip: try not to plant them all in the same area. This way, even if a fungal infection does occur, despite all your precautions, at least the eggs won’t all be affected.

This will give you the time you need to remove the bad ones to contain the spread.

Conclusion

Corydoras are easy to breed but difficult to multiply. That’s because the catfish have no parental instincts, so they won’t protect the eggs or the fry upon hatching.

You need to take on the role of a fish parent and provide the future fry generation with a separate breeding aquarium.

The only difference in water parameters, compared to the main tank, is water temperature. Provide the fry with slightly higher temperatures than the adults and feed them 2-3 meals per day, depending on their nutritional needs.

This will boost their growth rate and size, allowing them to join the general population sooner.

avatar I’m Fabian, aquarium fish breeder and founder of this website. I’ve been keeping fish, since I was a kid. On this blog, I share a lot of information about the aquarium hobby and various fish species that I like. Please leave a comment if you have any question.

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