You can usually find out if your fish gives birth to live young or lays eggs with a quick online search.This tells you if you should look for a bulging pregnant abdomen or tiny eggs in the tank.Raising young fish yourself can be difficult, so try to find out as much as possible about your specific species.
Step 1: This method is used for live-bearing species.
The most common live-bearing aquarium species are guppies, mollies, swordtails, and platies.Eggs are formed within the bodies of the males and females after they mate.The eggs hatch into fish and the mother gives birth over the course of a month or two.You can search for the name of your species to find out if it is live or egg-bearing.
Step 2: The males and females should be identified.
Male fish of live-bearing species are brighter or more elaborately colored, and have a narrow, long anal fin on their lower side.Females have a triangular or fan-shaped anal fin.If you know the sex of the fish, you can tell whether they are fighting or about to mate.An expert from an aquarium store may be needed for some species.
Step 3: There are some rituals to look for.
Different fish species can behave in different ways.In many gouramis, the male chases the females around and sometimes even causes damage.In discus, a male and a female will work together to defend one area of the tank from other fish.In either case, the male and female may turn upside down, wriggling around each other, or other subtle activities that are difficult to see.
Step 4: Check for a bulge.
There is a bulge at the back of the fish's abdomen.Over the course of 20–40 days, the abdomen grows into either a large, rounded shape or a "boxy" shape.The balloon mollies have a bulge just below the gills.There is a bulge in the front chest of overweight males.A female's pregnancy bulge will not shrink if you skip feedings for two or three days.
Step 5: There is a red or black spot.
There is a spot on the abdomen near the rear vent that pregnant female fish develop.Over the course of the pregnancy, this is usually black or bright red.When a fish is pregnant, it will grow brighter or darker.
Step 6: The young fish will be prepared.
Raising young fish, or fry, can be extremely challenging, and usually requires an entire separate tank so the adults or water filter does not harm them.If you're not ready for the task, try contacting an aquarium store or an experienced aquarium hobbyist who might be willing to help you or take the fish from you.If you decide to take care of the young, you can start with the section below on raising young but research your specific fish species as well.
Step 7: This method is used for egg-bearing species.
Eggbearers include discus fish, bettas, and most gourami species.The females of these species lay hundreds of eggs on the floor, wall, or water surface.If there is a male in the same tank, he may fertilize the eggs after they are laid.Eggs will hatch into live fish.It's a good idea to look for your species name online to find out if it lays eggs or gives live birth.The females of some fish species are able to store sperm for months before using it to fertilize eggs, so a new tank with females only can sometimes still reproduce.
Step 8: There are signs of a baby being born.
Some fish nest to keep their eggs safe.These may look like small pits, but they are not always seen.Gouramis can create elaborate nested from a mass of bubbles created by the male along the water surface.
Step 9: Check for eggs.
Some females of this species bulge as eggs grow inside of them, but this is not a major change and doesn't last long.Eggs look like balls of Jelly when they are laid.They are often scattered to the water, but in some species they end up in a mound on the floor or side of the aquarium.Gouramis are one of the many egg-laying species that have rituals.These can last up to a few hours and end with the eggs being deposited.
Step 10: The eggs will hatch.
Even if caught unaware, you will have time before the eggs hatch to care for young fish.If you want to raise your own fry, you should consult an aquarium store since the process can vary by species.Refer to the section on raising young fish for basic advice, but do not assume the method will work perfectly for every fish species.
Step 11: It's important to research your species as much as possible.
If your tank is suddenly full of young fish, the instructions below can teach you the basics.Taking care of young fish, or fry, is a real challenge, and the more you know about your specific species, the better.These guides will show you how to raise discus fish, gouramis, bettas, and guppies.Ask the employees at the aquarium store for advice.This is usually more useful than advice from a store.
Step 12: The filter should be replaced with a sponge.
Put in a sponge filter from an aquarium store if you have a water filter that sucks in water or creates a current.The current could exhaust the young fish or even suck them into the filter and kill them.
Step 13: The fish should be separated.
The eggs or young are moved into a completely new tank by fish breeders.It can be difficult to make a safe, stable water environment on short notice if you aren't an experienced aquarium caretakers.You can use a plastic net from the aquarium store to separate the fish.To find advice that matches your fish, try to find it online.If you can't separate based on parental behavior, use the net to divide the parents and eggs on one side, and the other fish on the others.All adult fish should be on one side of the net if the mother had a live birth.The young fish should swim through the net.
Step 14: Feed the fish fry.
You can sometimes purchase a specialized "fry food" product from aquarium stores, but often you'll need to choose from an array of other options.Liquid fish food and rotifers are usually safe.Depending on the species and size, the fish may need additional food as they grow.If you want advice on your fish's species, ask an aquarium store employee.Feed the young fry hard boiled egg yolk if you can't get to an aquarium store.
Step 15: As adults, plan how to care for them.
If you want to keep some of the fish, set up another tank.Inquire about how to sell or give away your young fish once they reach a certain age.