Some types of tropical fish are easy to breed at home, especially livebearers such as mollies, guppies, platies and swordtails. These are prolific breeders who give birth to live babies rather than laying eggs. While breeding these fish is easy, successfully raising baby fish requires extra care and special attention to aquarium conditions.
Separate the baby fish from any adult fish, as most adult fish will eat baby fish. Put baby fish in a separate tank or use a net breeder or a tank divider to isolate babies within the same tank. Use caution when netting baby fish to move them, as they are delicate.
Use a sponge filter or cover the filter intake with sponge or netting to prevent baby fish from being sucked into the filter. If you are using a single divided tank, keep the baby fish in the side of the tank away from the filter.
Place a thermometer in the tank and keep the temperature between 24.4 and 27.7 degrees C. Use an aquarium heater to regulate the temperature. A warmer temperature will help the fish grow faster, but do not raise it above 27.8 degrees C.
Check your water quality often. There should be no detectable levels of ammonia or nitrite.
Change 20 per cent of the water in the tank several times a week. Replace the water with tap water treated with a water conditioner to remove chlorine. Make sure the new water is close in temperature to the water in the tank. Frequent water changes help baby fish grow quickly, but never change more than 20 per cent of the water at a time.
Feed the babies a small amount of food four to six times daily. Baby fish thrive on live food such as baby brine shrimp, infusoria (a type of plankton) and microworms. They also can eat regular flake fish food that has been crushed into a fine powder.
Release the baby fish into the main tank when they are big enough and fast enough to avoid being eaten by other fish. Generally this is when they have doubled in length since birth, but consider the size of the other fish in the tank when deciding when to release babies. Water quality and temperature, food quality and stress level all influence how quickly the baby fish will be large enough to release.
Research the needs of your specific species of fish. While most tropical fish will eat their babies, some breeds such as Convict Cichlids protect and care for their young. Consider giving away some of your baby fish or selling them to a pet store when they are large enough. You will likely have too many fish for your aquarium.