How to Breed Black Mollies

Black mollies are an easy fish to care for as well as being attractive and sociable with other freshwater fish. Because black mollies are able to breed so often, it is possible to breed them five times a year and have them produce as many as 50 to 60 babies each of those times.

Things You'll Need

  • Male and female mollies
  • 15 gallon aquarium
  • Protein source such as blackworms or brine shrimp
  • Isolation tank
  • Fry food
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Instructions

    • 1

      Allow male and female black mollies to live together or buy a pregnant female. Female black mollies that are kept with males are pregnant most of the time. Females are larger than males and are rounder in the middle. Looking around a tank full of mollies will quickly make it evident which fish are female and which are pregnant. A pregnant female is simply rounder around the middle than the other females. It is also possible that all of the females in the tank are pregnant and that the obvious pregnancies are the ones that are the farthest along.

    • 2

      Keep a pregnant female in a tank that is 15 gallons or larger. Mollies will not stay as healthy in a smaller tank and the babies will be far less likely to survive.

    • 3

      Make sure the water is clean. Replace about 50 percent of the aquarium water every week. The water should be kept at about 80 degrees F. A heater or an aquarium light can usually maintain this temperature, but keep a thermometer in the tank to make sure that the temperature is kept constant.

    • 4

      Feed the mollies flakes and supplement them with brine shrimp or black worms. The brine shrimp can be live, dried or frozen, but the black worms should be live. A couple of black worms each day per female are enough.

    • 5

      Separate the pregnant female from the male fish. Males can stress a female during her pregnancy and stress can endanger the babies. If you have a large population of black mollies, keep only one or two males with the females to keep stress to a minimum. If there is only one male and one female, remove the male to make the pregnancy easier for the female.

    • 6

      Keep the female in something that will isolate her from her babies to make sure that she won't eat them. Black molly mothers are notorious for eating their offspring and they should not come into contact with them until they are large enough to be seen as something other than food. If there are other fish in the tank, get an isolator that has small holes in it that will allow the fish to leave the birthing area and swim around the rest of the tank. If there are other fish in the tank, keep her in a hatchery that has two compartments, one for her and one for the babies. The babies will swim to their own compartment through small holes and should be kept there for a few weeks until they are large enough to join the rest of the population.

    • 7

      Feed the baby mollies fry food. This can be bought in a pet food store or you can make your own by crushing flake food into powder. Feed the babies the powdered food twice a day.