Molly fish breed easily and frequently, but they aren’t fish that will continue caring for their fry after they’re born. In fact, adult mollies most often end up abandoning or even eating their fry.
If you want baby mollies to survive, you’ll need to care for them yourself by separating them from adult fish and feeding them foods suitable for small fry.
In this guide, I will teach you how to care for baby mollies including how to save them from adult fish, how to feed them and how to maintain a molly fry tank.
How Mollies Are Born?
As live-breeders, mollies spawn completely formed fry that skip the egg stage and are ready to swim and feed in just a couple of hours.
Molly males become reproductive at 12 months, while females reach reproductive age at 6 months. Female mollies carry the eggs for about 30-45 days.
There aren’t any special requirements for breeding, it’s enough to simply keep male and female mollies in the same aquarium and breeding will occur without any further intervention.
The female molly will have an enlarged abdomen and will start looking for shelter in a darker corner of the aquarium as she’s preparing to give birth to the fry.
Spawning usually takes place in the early hours of the morning and the fry of some molly breeds are rather large (e.g. black molly fry).
The fry will hide in the leaves of the aquarium plants and they’ll stay low for a couple of hours until they’re ready to feed and swim.
How to Save Molly Fry?
If your molly fish produced fry in a community aquarium, don’t expect the fry to survive. Adult mollies and other fish will certainly mistake them for a tasty snack.
If you want to avoid spawning to occur in a community tank, avoid keeping both male and female molly fish in the same aquarium.
However, in cases of misidentified gender, it may happen that even against your wishes, female and male molly fish may end up in a community aquarium and breed.
Below, I’ll discuss some of the ways you can salvage the fry when they’re born into a community aquarium.
Ideally, you should have a separate breeding tank for the female molly fish and the breeding tank should match the parameters of the origin tank.
After the female molly fish has dropped the fry, you should remove her, so you can continue caring for the fry yourself and prevent the female molly from eating the fry.
Now, even if you don’t have a separate breeding tank, there are ways to save at least some molly fry:
- Use a large plastic container or glass jar to extract the female as she’s about the give birth and keep her separated from the other adult fish in your tank. Once she has dropped the fry, you can remove her and continue caring for the fry.
- A second method to separate the female molly fish and the fry is to install a breeding box into the main tank, which is a plastic mesh or container that’s designed to allow water to flow through, without allowing other fish into the mesh.
This method is the easiest if you don’t want to worry about matching the water parameters of the main tank as you would have to do with other methods of separating the fry from the adults.
- The third option is less desirable and its success rate in saving the fry isn’t as high, but it can help if you’re caught off guard. Adding plants to the tank such as java moss, hornworts, guppy grass or roots of water lettuce can provide hiding spaces for the fry for a few weeks until they grow large enough to not be mistaken for food by the other fish.
The next step in caring for the fry will depend on which method you’ve chosen from the above. If you’ve chosen to use a glass jar or plastic container, depending on its size, you may need to transfer the fry in a nursing aquarium, where you can offer them the proper conditions for growing.
Likewise, you can’t keep them in the breeding box for too long either.
How Long Can You Keep Molly Fry in a Breeding Box?
Setting up a breeding box is probably the easiest way to save molly babies from being eaten by adult fish.
However, you shouldn’t keep them more than 2 weeks in the breeding box, because this will significantly stunt their growth, which is undesirable regardless of whether you’re raising mollies for commercial purposes or as a hobby.
Larger mollies can release as many as a hundred fry at once, therefore, it’s easy to understand how so many fry can quickly outgrow their breeding box.
At about 2 weeks, molly juveniles are large enough to not be mistaken for food anymore and you can release them into the main tank or you can set up their own aquarium.
Feeding Molly Fish Fry
For fast growth, molly fish fry need a diversified diet and require frequent feedings with small amounts of food. These fish are constantly hungry because of their fast digestion cycle.
Since molly babies are so small, their mouth opening is also very small, therefore, you’ll need to procure size-appropriate foods that will fit their mouths.
The digestion cycle of molly fry is short, therefore, they’ll be ready to eat as soon as every half hour. You shouldn’t feed them that often, of course, but you should aim for at least 5 feedings a day.
As with any fish or fry, overfeeding can be a problem. Also, scoop out any uneaten food so as not to foul the aquarium.
If you’re keeping molly juveniles in the same tank with the adults, you can feed them whatever you’re feeding the adults, just remember to crush the flake foods or larger foods, so it will fit their mouths.
There are flakes like First Bites designed for feeding small fry, so you can opt for those instead, especially that they’re rich in protein to sustain rapid growth.
Live foods are another excellent food choice for small molly fry, and you can opt for baby brine shrimp, vinegar eels, daphnia, micro worms. If live food is not available, frozen or freeze-dried can be a good alternative.
Another protein-rich food source that I like to use when feeding small fry is hard-boiled egg yolk made into a paste. It’s easy to prepare, readily available in your fridge, and not to mention very cheap. I add small amounts of the paste once or twice a day.
A varied diet will strengthen the fry and will stimulate their growth.
Molly Fry Tank Maintenance
If you haven’t set up a separate tank for your mollies and you continue to keep them in the same aquarium with the other fish, tank parameters should be kept stable and water changes should be regular as molly fry are more sensitive to high toxin levels.
If you decide to set up a nursery tank for the fry, here’s what you should aim for:
1. Tank Size & Filtration
Depending on the number of molly babies, set up a tank between 10 and 20 gallons. Add a fry-safe filter system to keep the water clean in addition to performing regular water changes.
Add some plants to the tank too such as java ferns and grasses.
Aim for a temperature a little above the temperature in the main tank (80 °F maximum). Warmer water speeds up metabolism and encourages the fry to eat more. In turn, this will help them grow faster.
To keep the aquarium heated at the optimal water temperature, you’ll require a heater to ensure consistent temperature.
3. Water Changes
To keep toxin levels low and refresh the water, aim for frequent partial water changes. I recommend 50% water changes twice a week. This will also facilitate the growth of your fry.
Water changes, of course, also depend on the number of fry you have and the size of your tank. Depending on how you stock your tank, you may get away with fewer water changes or you may need to perform more frequent water changes.
Offer your fry 12-16 hours of light each day and 6-8 hours of darkness for rest. Good light conditions will ensure the healthy development of your fish.
Now that you know more about breeding mollies and caring for baby mollies, you can look forward to breeding your molly fish.
As you can see, raising molly fish fry isn’t particularly difficult, but you do need to take some precautions to save the fry and to maintain optimal tank conditions.
Unlike adult molly fish that are hardier, the fry is more sensible to high toxin levels or sudden changes in water temperature.
I encourage you to familiarize yourself with their requirements before attempting to breed molly fish. Feed them a varied diet, keep their water clean and tidy, and you’ll be rewarded with healthy and active fish.