Is My Cardinal Tetra Pregnant?| How Do I Know It?| Facts About Their Pregnancy

Fish are fascinating creatures. Not only do they have the ability to breathe without lungs, but they also have some of the most beautiful colors in the animal kingdom. One of these beautiful fish is a cardinal tetra. These fish have a vibrant red coloration with black vertical stripes that run down their body. But how do you know if your cardinal tetra is pregnant?

Cardinal tetras will show some signs when they are pregnant. Such as noticeable weight gain, which is a sign of them being pregnant. They will also look slightly fatter in the middle and more rounded on top. Another thing to watch for is swelling or redness in bellies that may have some light-colored spots on them as well.

If you are new to fishing keeping, there are many things you need to know about Cardinal tetras. Read on to find out everything you need to know about Cardinal tetras.

How Do Cardinal Tetra Breed?

Cardinal Tetras reproduce sexually. This means they need a male and female to breed successfully. They will choose the most suitable partner based on their coloring, so you should keep at least two of each sex in your tank for breeding purposes.

The breeding process can take several weeks. How long it takes depends on the compatibility of your Cardinal Tetras and the water conditions in their tank. If they are ready to breed, you will notice some changes inside them and outside.

After spawning, the Cardinal Tetras will lay their eggs on plants, leaves, or any other object in your tank. The parents should guard them until they hatch and then care for their fry as if it were another batch of eggs. How long this process takes depends entirely on the water quality and temperature inside your aquarium.

When Do Cardinal Tetra Mature Enough To Be Pregnant?

Cardinal tetras attain sexual maturity at a young age. They become sexually active in the wild when they are less than six months old, and this is roughly equivalent to one year for most home aquariums.

Their reproductive cycle begins from April through September/October in the wild, with spawning occurring during the summer monsoon season. However, in aquariums, breeding can happen all year round with no specific seasonal trigger.

Cardinal tetras generally spawn in small groups consisting of one male and several females. After releasing eggs into the water column, both sexes will swim around to mix sperm with eggs before fertilization.

How Do I Know If My Cardinal Tetra Is Pregnant?

The best way to find out whether or not your females are pregnant or not is to watch your fish. Some of the common signs of pregnancy in Cardinal tetra are:

  • getting a distended stomach
  • an increase in appetite or eating more food than usual
  • change in the skin color
  • the fish may become more aggressive
  • redness in the bellies and underneath the tails
  • a dark stripe along the stomach

How To Take Care Of Pregnant Cardinal Tetra?

Pregnant cardinal tetra is more sensitive than usual. So, after the breeding process, you need to be very careful and watch your pregnant fish closely. Some of the ways to care for pregnant Cardinal tetras are:

Don’t Change The Water

Don’t change the water and don’t clean the tank. Pregnant fish needs a lot of care and attention. If you remove your pregnant Cardinal tetra from its habitat, it might cause severe problems as they are susceptible during this stage. So, wait until they ultimately give birth to their eggs before you can try to move them to another place.

Keep The Pregnant Cardinal Tetra In A Separated Area

Please keep your pet in separate areas, like you should keep them separate in the breeding tank. This is to make sure that they do not eat their eggs and also be able to protect the expecting female fish from other aggressive fishes or even your male Cardinal tetra who might harm them while protecting his unhatched eggs.

Add Some Plants

Adding some plants will help you a lot during this time because pregnant Cardinal tetras will hide behind the plants and lay their eggs. Also, make sure that you do not add any other fishes during this period because they might eat your pregnant fish’s eggs or harm them.

Provide A Safe And Peaceful Environment

To keep a peaceful environment for her baby, you should avoid adding anything new to your tank. Also, make sure that the pH levels are between 4.6 and 6.2 as they prefer this environment.

Add Some More Feeding

Provide more nutrients for them during their breeding period. You can increase feeding a bit but do not overfeed because it will spoil water quality which is very dangerous for both mother and her babies. Keep in mind that you should feed pregnant fish at least twice a day, and you can also add some more vitamins to their food during this period.

Provide Proper Lighting

You should provide proper lighting for your fish because they need it. If there is not enough light, then the eggs will die, and that would be very sad to see all those unborn babies die in the tank.

Add Some More Oxygen

Make sure you have enough oxygen levels during this time, as pregnant fish cannot breathe well. So adding more oxygen will help them a lot and keep you from worrying about the fish.

Give More Space

You should give your fish more space because they need it, and this is another good reason to separate them into different tanks. If you do not provide enough space for pregnant fish, then they can feel stressed, which can be very dangerous for their health.

Some FAQs

How Often Will My Fish Give Birth?

The average cardinal tetra gives birth three or four times during its lifetime. But it may give birth once every other month.

How Long Does It Take For Cardinal Tetras To Hatch?

The gestation period for cardinal tetra is about 20 to 28 days. In the wild, it probably takes a few hours for this species of fish to hatch from its eggshell after its parents lay them. However, once in an aquarium setting, it can take three or four days up to a week or longer.

Does The Male Cardinal Tetra Take Care Of The Eggs?

The male cardinal tetra will not take care of the eggs, but he does protect them for as long as possible during their development and birth process. Unfortunately, he is also very territorial around this time, so it’s important to make sure both cardinal tetras are healthy before putting them together.

How Many Eggs Will, My Cardinal Tetra Spawn, At Once?

This will depend on the type of cardinal tetra you have. The larger varieties such as “Espejo,” “Celestial Eye,” and “Gold Stripe Cardinal Tetras” are more likely to spawn at once than their smaller counterparts. However, some fish may lay eggs several times for days.


There are many ways to determine if your Cardinal Tetra is pregnant. From watching for color changes, knowing the mating habits, and being familiar with the signs of pregnancy in fish. You should be able to tell within a few weeks whether or not she’s expecting.

If you find your Cardinal tetra is pregnant, be sure to provide her with a large and comfortable home that will support the growing fry.

Has your Cardinal Tetra become pregnant? What signs did you notice first? Please tell us in the comments.

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