Cory Catfish Eggs – Everything You Should Know

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If you like Corydoras, you will be pleased to find out that these fish are easy to breed. They only need a clean habitat with good food and adequate temperatures, and they will begin their mating dance immediately.

But if you’ve never owned Corydoras before, what should you know about the eggs and the fish’s breeding behavior?

Let’s have a look!

What do Corydoras Eggs Look Like?

Corydoras eggs are white and round, no bigger than 2 mm in diameter. If your Corydoras have bred, you should see the eggs in batches throughout the tank.

The female will lay them in groups of 10-20 pieces on various hard surfaces like plant leaves, rocks, substrate, etc.

The female’s instincts will drive it to spread the eggs throughout the tank so that at least some of them will survive predation and elements.

These dangers don’t exist in an aquarium, but the fish operate based on their biological programming.

When do Corydoras Start Laying Eggs?

Corydoras reach sexual maturity when they’re 6 to 9-month-old. At that point, your Corydoras will begin to mate, provided the fish has the right conditions for it.

If the mating process is successful, the female will soon start to lay the eggs, and you might even catch it in the act. Especially since it will lay several egg batches throughout the tank.

How Many Eggs do Corydoras Lay?

Corydoras lay up to 50 eggs in one spawning, although this number varies greatly. Some Corydoras females can only spawn 10 eggs, depending on their age, diet, environmental conditions, and other factors.

Larger species of catfish will lay more eggs, and some lay them in one batch, while others spread them out.

How Long Does it Take for Cory Eggs to Hatch?

Cory eggs take approximately 3-5 days to hatch, although some can take 7 or more days. The hatching time depends on the environmental temperature, as warmer waters will cause the eggs to hatch sooner.

The consensus is that cory eggs require temperatures between 72 and 78 F to optimize the hatching time.

This stays true for most fish eggs, although some species require even higher temperatures. This is an interesting point, given that adult Corydoras require colder-than-usual waters to get into their mating state.

While Corydoras are easy to breed, you should invest in a breeding tank to separate the couple and get it into mating state.

Lowering the water temperature by 3 degrees compared to the main tank will achieve just that.

Once the breeding process is complete, and the eggs are out, you should then remove the parents and increase the water temperature accordingly.

I suggest keeping the water temperature in the 75-78 range for optimal results.

The resulting fry don’t have any special requirements in terms of temperature. Whatever works for adult catfish works for them as well.

Do Corydoras Eat Their Eggs and Fry?

Yes, Corydoras can eat their eggs and fry if given the opportunity. They won’t go out of their way to do it, but they will if nothing else is available. This is an even bigger incentive to invest in a breeding tank.

This allows you to breed Corydoras successfully by minimizing the risks of the adult fish eating their own eggs and fry.

What to do When Your Cory Lay Eggs?

There are 3 things to remember once your Corydoras have laid their eggs:

  1. Not all eggs will hatch – This happens because the male cannot fertilize all of the eggs. Some will remain unfertilized, and you need to identify them quickly. Unfertilized eggs will soon develop a white layer of bacteria that consumes them and can spread to the viable eggs as well. You can tell which Cory eggs have been fertilized by assessing their coloring. Fertilized eggs will turn brownish after a couple of days, while unfertilized ones will remain white. So, remove the white ones.
  2. The adult fish may eat the eggs if you don’t remove them from the tank – We’ve already touched upon this point. Remove the adult catfish as soon as the egg-laying process is complete.
  3. You can contribute to the eggs’ hatching rate – Providing adequate care can help the eggs hatch sooner and improve the fry’s survivability rate considerably as well.

So, now that your eggs are all out, what can you do to support their development?

Consider the following:

  • Improve aeration – An air pump is necessary not only to boost oxygen levels in the water but also to create water motion. Both of these effects are necessary to keep the eggs fresh and safe from bacteria and mold.
  • Spread the eggs around – You don’t want the eggs latching together in a big pile. That’s because some eggs will inevitably go bad, and they can infect the others if they’re too close. Spreading them out won’t be quite easy, given that Cory eggs are sticky, so take your time, careful not to crush them in the process.
  • Use an antibacterial solution – Methalyne blue and eSHa 2000 are great antibacterial agents being used as bacterial deterrents in breeding tanks. These will eliminate bacteria without hurting the eggs or the environment.
  • Constant water changes – You may need daily water changes to prevent the accumulation of dirt and keep the water fresh and well-oxygenated. Just be careful not to disturb the substrate too much or suck any eggs in the process.

Also, always remember to remove any unfertilized eggs as soon as you spot them. After the eggs have hatched, your job is relatively easy.

The fry don’t need any special care to grow. Feed them a nutritious diet to support their accelerated growth rate and keep them in water temperature similar to the adults, and they will thrive.

Requirements for Breeding Corydoras

Fortunately, Corydoras are easy to breed. However, they still require special conditions to properly carry on with the breeding process.

Consider the following when breeding your Corydoras:

  • Choose the right couple – If you plan to breed your Corydoras, you should purchase your catfish with this purpose in mind. Choose 2 healthy specimens with good genes that are more likely to reproduce successfully and produce quality fry.
  • Feed live food – Your catfish should get more live food during the mating phase. Aim for bloodworms and various insects and larvae for a couple of days before the mating phase. The added protein will work wonders in preparing the fish for mating.
  • Drop the water temperature – The water temperature should be 3 degrees lower than usual.
  • Remove the fish from the breeding tank – The fish won’t waste too much time before starting the mating process. Once that’s complete, wait for the female to lay the eggs and remove the fish from the tank. This is necessary to prevent the catfish from eating the eggs.

There isn’t much more to it than that. The eggs will hatch within several days, and we’ve already discussed how to care for them in the meantime.

The resulting fry will grow fast with proper assistance and rich meals, and they should be ready to join the main tank within 2 months.


Corydoras are easy breeders, but they, too, require some assistance along the way.

Fortunately, you know now how to care for the eggs and improve their hatching rate considerably.

Author Image Fabian
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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