My Fish Gave Birth! Now What?

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If you have an aquarium, you might have to deal with newly hatched fish at some point. That’s right—you might be caught off guard when your fish become pregnant. Don’t panic; our fish experts and veterinarians are here to help you with your new and unexpected aquatic parenthood. There are a few scenarios in which you may find yourself unexpectedly playing host to quite a few new fishy residents; some fish will breed with your existing fish when introduced to your tank after purchase, while others may already be pregnant upon purchase. It can often be difficult to identify when a fish is pregnant, and depending on her breed your fish can give birth to anywhere from a dozen to a couple hundred fray at once.

Some aquarium fish carry the eggs inside of them. When the eggs are fertilized, they eventually hatch inside the mother, and the babies emerge in a live birth. Other types of fish lay hundreds of eggs in nests within the aquarium, in this case, the males fertilize these eggs, and then they hatch into live fish. You may not notice that any of this is happening until you see hundreds of tiny fish swimming around in your aquarium. By that point, is it too late to raise the little guys? Here’s how to handle pet fish care if you get surprised by the unexpected.

How to Identify a Pregnant Fish

Most types of aquarium fish lay eggs. If your fish is nesting, it may build a safe area for the eggs within the gravel. Some species build nests within bubbles at the surface of the water, in this case, you may notice jelly-like sacs floating throughout the tank. It’s not always easy to identify when a female fish is carrying eggs as the bugle that signifies her pregnancy can be hard to spot.

According to Animal-World, the most common fish species that give birth to live fish are mollies, guppies, platies, and swordtails. Frequently, the mating rituals of these species are mistaken as aggression. Within about 20 to 40 days after the mating ritual has concluded, the female will develop a bulge in the abdomen; a red or black spot may form toward the rear of the abdomen signifying her pregnancy. Guppies and mollies can deliver as many as 20 fry at once. Usually, your fish will have fewer babies her first pregnancy with the number of fry being delivered or hatched growing with each pregnancy.  

If you have a seahorse, which is indeed a type of fish, you may be surprised to learn that male seahorses become pregnant. After performing a mating “dance,” the female lays her eggs in the male’s pouch the male will then carry the eggs to term. Another fun seahorse fact, seahorses are monogamous!

Caring For Baby Fish

Raising baby fish successfully takes a lot of hard work, which can be made a little more manageable by following some simple guidelines.

  • For many species, it’s important to keep fertilized eggs and newly hatched fish, or fry, separate from the adults. Some fish eat their own young while others eat the young of other species. Keeping the fish eggs and fry separate from the adult fish may give them a better chance of survival.

  • When moving the fry to a separate tank, use the water from the original tank. Don’t use a net to transfer the baby fish, instead, scoop them up with a cup. This will prevent them from being harmed by the mesh of the net.

  • Some adult fish are caretakers. If you noticed a fish guarding its nest against other fish, you might be able to keep the parents in the same tank as the fry. Fish who were born via live birth traditionally are better off being separated from their parents.

  • Create a good home for the fry. Young fish are more susceptible to infection and disease than adult fish, so take extra care to make sure that their tanks are properly maintained. This process involves changing the water frequently, keeping ammonia and nitrite levels neutral, and adding some gravel from the parent tank to the fry tank can help balance the nitrogen levels. According to Fishlore, you should fully cycle the tank and test the water before adding the fry. Lastly, If you have a strong aeration system, you may need to turn it down in the fry tank. Agitating the water too much can harm the tiny fish. You don’t want a strong current to suck the fry into the filter.


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