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How Long Do Cory Catfish Eggs Take To Hatch?

How long do cory catfish eggs take to hatch? Usually, the cory catfish eggs hatch in three to five days. 

However, it mainly depends on two factors. There is a huge number of variations and colors of these beautiful creatures and the number of days taken to hatch primarily depends on the species of cory catfish. 

Secondly, the temperature of water in the breeding tank affects the number of days. 

Normally, it should be in the range of 70°F to 75°F (21°C to 24°C). You can observe the tiny wrigglers with the yolk sac attached to the aquarium bottom once they get hatched. 

You can feed them after the sac is absorbed. The recommended feed are microworms, baby brine shrimp, and other commercial fry food.

How Long Do Cory Catfish Eggs Take To Hatch

How many eggs does a cory catfish lay?

Well, they don’t lay hundreds of eggs like many other fish species do. Female cory fish can spawn from 10 to 20 eggs at a time.                                                       

How do Cory catfish eggs get fertilized?

The fertilization of the cory catfish is still not fully understood and there are two contradictories on the method of fertilization. 

The male presents his pelvic area for the female to attach to. The female presses her mouth against the male’s pelvic area forming a T shape. 

The male then releases the sperm. According to many ichthyologists, sperms collect in the gills of the female and then sperms push into a unique cup that she forms with her pelvic fins. 

Chicken Embryo 10 Days Video
Chicken Embryo 10 Days Video

After obtaining the sperms, the females lay 1-5 eggs into the cup described above. Then the eggs get fertilized with the sperms in the cup. 

The female then moves to the area that she has already cleaned before the mating. It is usually an aquatic plant or the aquarium glass itself. 

Then she glues the eggs individually to the chosen substrate. It can take anywhere from 1 minute to 15 minutes for the female to lay eggs each time. 

She repeats the same procedure several times. It can be the same male or a different one. After she gets 10-30 eggs in her clutch she stops the procedure. The whole procedure may last 3-6 hours.

According to some aquarists, the female cory collects sperms in her mouth. Then the sperms pass through her digestive tract to be released along with the eggs. 

How to tell if cory eggs are fertile?

You can simply observe the color of the eggs and tell whether they are fertile or not. 

The fertile eggs look off white to beige in color. As the hatching nears the eggs tend to develop a darker spot in the middle and this is a definite clue that the eggs are fertile. 

There is a fungus that inhibits fertilization. As long as the eggs do not develop fungus, the fry will most likely hatch successfully. 

The infertile eggs look plain, white, or translucent and it is easy to identify just looking at them.

Further, the shape of the fertilized and unfertilized eggs are different. The shape of the fertilized eggs is oval while the shape of the unfertilized eggs is a teardrop shape.

Do cory catfish lay unfertilized eggs?

Yes, they lay unfertilized eggs too. Do not disappoint if you see unfertilized eggs in your aquarium!! 

It is a common occurrence especially when the female Cory Catfish is introduced to a community tank

You can easily identify the unfertilized eggs as they are always laid on the tank’s bottom and are teardrop-shaped.

According to experienced aquarists, the female Cory Catfish lay unfertilized eggs for several reasons. 

It can be an act of aggression towards other fish, she may stress out because of the changing of the environment/aquarium or her body is producing more than one clutch of eggs at a time. 

Also, the female Cory catfish may lay the unfertilized eggs in an event where there is no male cory catfish in the aquarium.

Do cory catfish eat their eggs?

Yes. Cory Catfish have a tendency to eat their own eggs as many other spawning fish do

Therefore, it is crucial to transfer the adult Cory Catfish from the breeding tank as soon as the eggs have been laid. 

Before sending them to a separate tank make sure their spawning session is over because it takes 3-6 hours to end the session. 

According to the experienced aquarist, the most important and the hardest part of the breeding of corydoras is to separate the adults out of the tank  ASAP!!  For this, you have to look closely throughout the hours.

How to remove cory eggs from glass?

Corys will lay eggs anywhere, often on the glass, but also on the gravel, around or on plants, on the filter, or on decorations like rocks

It is good to send the parents into a breeding tank with no or fewer decorations so that you can collect eggs easily. 

There are many contradictories for the method of removing eggs. Some aquarists recommend using a razor blade or sharp edge card (like credit cards)  to scrape the eggs from the glass. 

However, this should be done very carefully as the eggs may destroy due to the shard edge of the blade/card. 

The most recommended method nowadays is to use the fingers of the owner to collect eggs. Gently roll the eggs into a net using your fingers. 

You can set a net inside the tank bottom to pick the eggs that are falling off while you collect them. This also should be done carefully. 

Whatever method you are using sanitize the razor blade and the hands because they may contaminate eggs. 

Different species of fungus may grow in the contaminated eggs and if you keep the contaminated eggs and healthy eggs together you will end up without any results. 

Due to the difficulty of removing eggs, many experienced people in the trade advise using a separate tank to breed and separate the adults after laying eggs and keep the eggs in the tank as it is. This is considered a good method so that you can take care of them easily. 

How Long Do Cory Catfish Eggs Take To Hatch

How often do cory catfish lay eggs?

Cory catfish like to mate with similar species and produce offspring regularly. Usually, each  female cory catfish lay eggs once every seven days

The frequency of egg-laying is depending on two major factors. Firstly, the egg-laying frequency depends on the number of cory catfish in your aquarium. 

The best range is having 6-8 cory catfish in one aquarium. You can expect eggs every week if you follow the above ratio. 

 In a 6-8 herd there is a high chance you will end up with few males and few female ones together. 

The number of Cory catfish present in the tank is the indicator that suggests how many times Cory catfish will lay eggs during the breeding season.

However, the egg-laying process and spawning behavior in both genders will be successful only when you maintain ideal water parameters in the breeding tank.

Apart from those major factors following factors also affect the egg-laying frequency. 

  • Their food
  • The lighting
  • Tank size
  • Water temperature
  • General fish health
  • Environmental factors like plants

You can anticipate the egg-laying frequency by keeping those factors at their optimum level. 

How do you take care of Cory’s catfish eggs?

There are a few steps of take care of cory catfish eggs. 

1. Remove the eggs from your tank.

As stated above adult cory catfish eat their own eggs. If the breeding takes place in a community tank other fish also can feast on the eggs.

Therefore, you need to separate eggs and adults or other fish to ensure the high hatch rates. 

You can either separate adults from the breeding tank or send the eggs to another tank. If you plan to transfer the eggs to another tank, wait around one hour after the spawning before picking eggs. 

The eggs which are just released are very fragile and they get hardened with time. The hardened eggs are relatively easy to pick than the just laid fragile eggs and also the percentage of damage while collecting gets reduced.

As described above you can use a credit card, razor blades, or your fingers to collect the eggs. Since the sharp edges of razor blades and credit cards damage the eggs, it is better to use your fingers to collect them. 

2. Set up a separate container

There are different types of breeder containers available in the trade. Simply, you can use a plastic container that is not too big or too small.

Some people use professional breeder boxes too. However, it is good to use a tub that can place in the tank since the water needs to be heated. 

Egg tumblers do not work well with the Cory Catfish eggs. Since the eggs are very sticky, they stick to the inside of the tumbler. Therefore, you can use a regular tub that does not cost like tumblers.

You need to keep the aeration of the tub in the optimum range as it reduces the chance of infections that harm the eggs. 

Further, the developing eggs need a good amount of airflow. Therefore, add some form of aeration to the breeding tank. 

An air pump works best for this. You just need to attach an airstone to the tubing. Apart from increasing the oxygen levels, the bubbles created by air pumps make good aeration. It reduces the chance of the eggs turning bad.

If you don’t have an air pump, simply attach the tube close to the outlet of the tank. Poke some small holes and ensure that a good amount of flow is getting to the eggs. 

It is advised to spread out the eggs as much as possible. It decreases the probability of spreading the fungal diseases from infected to healthy eggs.

3. Add an antibacterial agent.

There is a possibility of contaminating eggs while you try to collect them. Also, the eggs can be infected by fungal diseases.

Therefore, to prevent such contaminations, it is good to add some extra substance. A few options used by the aquarists are listed below.

  • Methylene blue is the most common reagent.  Add 1 teaspoon of 2.303% Methylene blue per 10 gallons of water.
  • eSHa 2000 is another popular treatment that is often used by breeders in European countries. Use it three days in a row: add 6 drops per 5 gallons of water on the first day. On the second day halve the number of drops and add 3 drops on the third day.

In the wild, the Cory catfish often lay eggs against leaves, which prevent infections. If you don’t have the above solutions you can use Catappa or Indian almond leaves as an antibacterial agent.

While acting as a good natural alternative, the almond leaves cultivate micro-organisms that serve as the first food for the fry.

Make sure to remove carbon in your filter (if it contains any carbon) as it neutralizes the power of the solution.

4. Change water every day

You need to keep the water in the tank in good condition. It is recommended to change the water one to three times a day if you put the eggs into a separate tub.

Changing water regularly, will enhance the development of the eggs and again, reduce the chance of infections.

5. Remove unfertilized eggs

Cory catfish lay fertilized and unfertilized eggs as stated above. It is vital to pick the unfertilized eggs in order to protect the good eggs from infection.

You can easily identify the unfertilized eggs by observing their shape and color. 

You can use tweezers to remove bad eggs. Another method is sucking them out with an air hose during the water change

How long are Cory catfish pregnant?

Usually, we don’t call “ pregnant “Cory catfish species because they are egg-laying species. Once they become mature, female fish starts to develop and carry eggs in their stomach.

During this time you can observe a prominent round or boxy bulge on its abdomen region.

Female fish releases eggs after a week of being wooded by the male. After laying eggs her gravity body becomes normal.

Will corydoras breed in a community tank?

Yes, they do. However, the survival rate may be lower due to the eggs can be good food for the other fish (and their parents too) in the aquarium.

If you see such eggs in your aquarium remove them and transfer them to a breeding tank.

Credit to : Jadren Aquatics

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About Dr.Chamika

Hello, I'm Dr. Chamika. I am a Researcher in Water quality, Aquatic organisms, and Environmental chemistry. I am a passionate fish keeper, with10 years of experience. My mission is to help other aquarists experience the joy of fish keeping.