How to Encourage Mollies to Breed

Mollies breed readily in a home aquarium. They give birth to live young, with a high survival rate, rather than lay eggs. For these reasons mollies are one of the best species for people breeding fish for the first time. Although they are hardy, mollies are more likely to breed if you provide the ideal conditions. If your fish appear healthy and happy but have not yet bred, and you are certain you have at least one male and one female, try a few tricks to encourage them.

Things You'll Need

  • Aquatic plants
  • Live food
  • Second freshwater tank
  • Aquarium salt mix
  • Mollies
Show More

Instructions

    • 1

      Increase the tank temperature gradually to 80 degrees Fahrenheit. This is the upper end of the ideal range for mollies and may encourage breeding. If the tank was too cool before, that might well have been the problem.

    • 2

      Introduce aquatic plants, including floating varieties, if the tank is not already well planted. Obtain the plants from an aquarium, not garden, supply store and rinse well in dechlorinated water before adding to your tank. A natural habitat with plenty of places for the adult mollies and any fry (baby fish) to hide relaxes the fish and makes them more likely to breed.

    • 3

      Supplement the mollies' diet with live food such as daphnia and bloodworms. This conditions the fish for breeding. Feed as much live food as the adults can eat within about 10 minutes a couple of times a week. Leftover live food is not a problem, because the little creatures will live in the tank until they finally get eaten, but feed less next time.

    • 4

      Transfer the mollies to a dedicated molly tank, if you have been keeping them in a community aquarium. The presence of other fish might be stressing your mollies. The mollies might even have already bred, but other fish ate the fry before you noticed. A dedicated tank also allows you to create the perfect conditions for mollies, which may not be suitable for the other fish. Set up the second tank like the first one. Allow it to cycle for a week before transferring the fish. You might also have to remove the mother mollies from the second tank once they have given birth to the live babies. Mollies have been known to eat their fry.

    • 5

      Add a salt mix to the water at a rate of approximately one teaspoon per gallon of water. Mollies are naturally a brackish, not freshwater, fish. They cope with a freshwater setup but may do better in a brackish environment.

    • 6

      Introduce a few new mollies from a couple of different varieties. While careful separation of strains is necessary if you are trying to breed purebred mollies, you might get healthier fry through crossbreeding, although the fry won't be very valuable. The inbreeding necessary for purebred animals can lead to genetic problems, which could lead to breeding problems.