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Molly fish reproduce at a rapid rate and produce a lot of fry, so it’s important to know about their reproduction mechanism to be able to control their population, especially if it’s your first time keeping mollies.

Some fish are more difficult to breed in captivity, some don’t breed at all, but mollies are prolific breeders that don’t seem to mind breeding in captivity.

If you’re planning on keeping mollies, one of the questions you’re probably asking yourself is: How do mollies reproduce?

molly-fish-lay-eggs

So, do mollies lay eggs or are mollies livebearers? I’ll answer these questions and more about molly fish reproduction in this article.

Are Molly Fish Egg Layers?

No, molly fish do not lay any eggs, they give birth to complete fish that are ready to swim and feed in a matter of hours.

This doesn’t mean that they don’t produce eggs, however. They do. The difference is that the eggs are kept inside the body and only when they hatch, are the fry released by the female molly.

During the pregnancy, the eggs are store and develop in the belly of the female molly fish. When the eggs hatch, the female drops the fry directly into the aquarium.

Female mollies can store up to 100 eggs in their bodies, and even more in the case of larger molly fish breeds.

Even though mollies will eat their fry if left in the same aquarium with them, they still breed fast and each pregnancy produces a lot of fry, so it’s easy to see how things can get out of control.

In the following video you can see how a big female molly gives birth to molly fry:

How do Molly Fish Reproduce?

Placing molly females and males into the same aquarium is pretty much all that’s required to breed mollies.

Because male molly fish constantly pursue females, it’s enough to place a single male to three females, otherwise, multiple male will stress out females.

Molly fish reproduce using internal fertilization. That is, the male molly fertilizes the eggs while they’re still inside the female, unlike with egg-layer fish, where fertilization occurs after the eggs have been laid.

How Often do Mollies Reproduce?

At 6 months of age, female mollies are already ready to reproduce, and they’ll carry the eggs for 30-45 days. Female mollies can store the sperm for months and fertilize the eggs monthly even when no males are present.

While keeping same gender fish in your tank is a good idea to control their population, this may not always work for mollies precisely because female mollies can store the sperm for so long.

Therefore, even if you stock your aquarium only with female mollies, it’s possible that some of them are already pregnant and you’d still end up with fry.

At this rate, female mollies can give birth every month or so. If you don’t want any fry, you should stock your tank with male mollies.

If you’d like your mollies to reproduce, is enough to stock a single male to three females.

Molly Fish Fry

Molly fry are very tiny when they’re born, so it is perhaps not that difficult to understand why fish mistake them for food so often.

And while allowing adult fish eating fry is a way to keep their population under control, if you want to breed mollies, it’s understandable that you want to prevent adult fish eating the fry.

Unfortunately, molly fish aren’t good parents and they should be separated from the fry as soon as the female molly fish has given birth.

Placing a breeding trap or breeding box in the home aquarium is one way to prevent the adults from eating the fry.

Another way is to remove the female guppy and place her in a separate tank, where she can give birth, and then place her back into the home aquarium, raising the fry on your own.

If you have a well planted aquarium, you may get away with breeding mollies even in a mixed-breed aquarium, if the fry can hide from adult fish until they grow big enough not to be mistaken for food.

Either way, if you’re serious about breeding molly fish, you need to focus on keeping them safe from adult fish that are more than happy to eat them.

Feeding the fry is not particularly challenging, the only difficulty is that since they’re so small, their mouth opening is also very small. Therefore, you need to feed them special foods that fit their mouth.

Crushed flake foods, hard-boiled egg yolk paste, and special food designed for small fry are all good options when it comes to caring for molly fry.

Live foods like freshly hatched baby brine shrimp and microworms are also good alternatives to the standard commercial foods.

Livebearer Fish Species

Molly fish aren’t the only livebearer fish species. Although not all have the amazing reproduction rate of mollies, most of the things you’ve read in this article about the way they reproduce and their behavior during this time applies to most livebearer fish.

Some popular livebearer fish species include guppies, platies, swordtails, endlers, but more than 200 other species fall into the livebearer category.

Some livebearers thrive both in freshwater and brackish water and only a small number of them are fully marine.

Most livebearer fish can be introduced to aquariums and breed without problems in captivity too. Although their lifespan is longer in the wild, with careful aquarium planning, optimized water conditions, and a healthy diet, you can offer these fish a long life even in aquarium conditions.

Make sure you research the keeping requirements of any livebearer fish you’re planning to keep, so you can match the conditions of their natural habitat as closely as possible.

Conclusion

Now that you know more about how molly fish reproduce and that they do not lay eggs, you attempt to breed them yourself or, on the contrary, prevent them from breeding and keep their population under control.

I hope my article has been useful for you in understanding molly fish breeding habits and has prepared you for what you can expect when breeding them.

Written by Fabian

Hey, I'm Fabian, chief editor at Aquarium Nexus. I really enjoy the aquarium hobby and love sharing my experience with others. If you have any questions feel free to contact me or leave a comment below.

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