Do Silver Molly Fish Give Birth or Lay Eggs?

Silver mollies are a selectively bred variety of molly. The exact species who came together to spawn the silver molly is hard to nail down, because several species of mollies show up in the aquarium trade, and hybrids are common. But silver mollies, like all mollies, belong to the livebearer family, Poeciliidae, well-known for birthing live young.

  1. Broods

    • Like other livebearers, silver mollies hatch their eggs internally and allow the young to develop before releasing them. Depending on the exact species of molly and the water conditions, gestation can take four weeks to eight weeks. A single brood -- or batch of offspring -- can consist of as many as 200 fry or baby fish. Silver mollies are born as miniature versions of the adults, better equipped to survive than egg-laying fishes' fry. However, silver mollies are cannibalistic and will eat their own young if given half a chance.

    Mating

    • In silver mollies, a single mating can produce multiple batches of offspring. Biologists term this ability "superfecundity." On top of this, males constantly try to mate, so it's a good idea to keep silver mollies and all livebearers in a ratio of at least two females per male. Given the ability to bear multiple broods from a single mating and males' constant amorous advances, female silver mollies tend to be more-or-less permanently pregnant.

    Breeding Conditions

    • Silver mollies are slightly harder to breed than most livebearers. However, in the case of silver mollies, this just means they need their ideal water chemistry provided in order to mate. Mollies thrive in alkaline aquarium water with a pH of 7.0 to 8.5. Also, silver mollies need some salt in their water to really thrive. While silver mollies can survive in pure saltwater, 1 teaspoon per gallon is enough for them to feel healthy. If you meed these conditions, your silver mollies will breed regularly.

    Breeding

    • If you want to breed silver mollies you will also need to take some steps to discourage predation. There are two main ways of doing this. You may densely plant the aquarium, which will allow a few fry from each brood to grow large enough to avoid parents with the munchies. You will probably have to use fake plants, since live ones tend to die in water with aquarium salt. However, to ensure as many fry survive as possible, you can take gravid females -- silver mollies with swollen bellies about to give birth -- and place them in a separate aquarium. After the female gives birth, return her to the main tank and care for the fry in their new tank.