What Do You Do With Molly Fry? (5 Practical Options)

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A batch of molly fish fry can catch you by surprise. That was what happened to me a few years back. Seeing those little creatures swimming around raises one central question: what do you do with those fry?

These are the five courses you can take with recently born molly fry:

  • Raise the babies in a dedicated nursery.
  • Sell the molly fry to a fish store.
  • Give the babies away to other aquarists.
  • Trade your baby mollies for other fish.
  • Leave the fry in the community tank.

As we move forward, I will elaborate on the different steps you can take with a new batch of molly fish fry. Then, I’ll discuss what you can do with unwanted molly babies or any fish fry, for that matter.

Also Read: Molly Fry 101

A couple of days old molly fry, swimming in its nursery.

What Do You Do With Molly Fry?

On average, Molly fish will add 40 to 100 babies to your tank, and they do so every 60 days. Mollies don’t need your permission to reproduce. 

You can create a conducive environment that encourages mating, but if you have both genders in the same water, they can still mate without your direct intervention. 

Reproduction is just the first step. What happens when the babies enter your tank? You have five primary options:

1. Raising The Babies

Many aquarists choose this option. They want to raise their baby fish to adulthood because it allows them to multiply their molly fish population. 

But raising molly fry is easier said than done. You have to keep the following in mind:

  • Tank Size

Molly fry are vulnerable and sensitive. Therefore, you must create a healthy aquatic environment that enhances their growth. 

That means securing an aquarium of at least five gallons.[1] Twenty gallons would be the better option, especially if the mother gave birth to a hundred or more babies.

But the babies can survive in 5-gallon tanks if the need arises. Aim for 20 gallons if you want the nursery tank to house the mother before she gives birth.

  • Filter

Every tank requires a filter, and nursery aquariums are no different. Molly fry are somewhat messy because they eat multiple meals a day.

And unfortunately, the more food a fish eats, the more waste it produces. You can also expect the volume of leftovers to increase.

Therefore, I suggest installing a mesh-covered filter that can remove pollutants without sucking the babies in.

You can also go with a sponge filter. I personally use the Lefunpets Sponge Filter (link to Amazon). I install it whenever I wish to grow tiny creatures like fish fry and shrimp.

  • Plants

Molly fry do not have a preference where plants are concerned. Therefore, you can experiment with species that are easy to take care of, including Java Moss, Amazon Sword, and Hornwort.[2]

Plants are excellent because they provide both oxygen and hiding spots. These are two crucial elements for the survival of molly fry.

Amazon Sword (Echinodorus amazonicus) in a freshwater fish tank.
  • Parameters

Use a heater to maintain a temperature of 75 to 80 degrees F (24-27° C). You should also check the pH (7.5 to 8.5) and hardness (12 – 25dGH).

Also, the ammonia and nitrite should be kept at 0 ppm while nitrates are below 30 ppm. If the parameters are wrong, adjust them gradually. Otherwise, significant shifts will harm the babies.

  • Food

Molly fry can eat the foods their parents enjoy. However, you have to grind them into tiny pieces that can fit the mouths of the babies. Prioritize live foods such as vinegar eels and blood worms.

A study exploring the impact of different feeds on growth found that aquarists could influence development by altering the protein levels in a fish’s meals.[3]

However, you don’t have to overthink a molly fry’s diet. Just remember to give them at least five meals a day.[4]

2. Selling The Babies

Some aquarists raise molly fry because they want to observe the creatures in their natural habitat. For others, baby mollies are an income source. You can sell them to fish stores or other aquarists.

However, you must rear the creatures in significant numbers to make a decent profit, as molly fish are cheap. Unless you can raise the majority of your babies to adulthood, this practice is not worth the hassle.

Recently born molly fry, searching for food on driftwood.

3. Giving The Babies Away

It takes a lot of resources to raise fish. Fish stores can afford to undertake this task because they have dozens of tanks and more than enough fish to profit from the activity.

But if you have one or two molly fish tanks, you are better off donating excess babies to other aquarists. The internet is full of aquarists looking to experiment with fish.

You can find them in forums, Facebook groups, etc. They will appreciate any free molly fry you send their way. You can also disseminate the creatures among your friends and family. 

4. Trading The Fish

Believe it or not, aquarists are more than happy to trade their fish for suitable replacements. Why buy more fish when you can simply exchange your molly fry for offspring from a different species?

If you start searching, you might be surprised by the number of people in your area looking to swap fish. You can also trade your baby mollies for adult fish of different species.

5. Letting Nature Run Its Course

Your last option is to leave the molly fry in the community tank. With this option, some of the babies will probably get eaten by other fish unless you have a lot of hiding places.

While this option sounds a bit cruel, you’ll be surprised to learn that many aquarists raise fish fry to feed adult fish.

If you don’t want all of them to die, introduce dense vegetation. I personally like floating plants with brushy roots, such as Amazon Frogbit, Red Root Floater, and Water Lettuce.

I found that fish fry use these to hide from predators. But don’t get discouraged if some of your fry are being eaten. Even under ideal conditions, on average, fifty percent won’t survive.

A molly fry nursery featuring close to 100 molly babies.

What Can I Do With Unwanted Molly Fry?

Many aquarists respond to mating among mollies by buying bigger tanks to house the offspring. But what if you can’t afford a bigger tank? 

What if you don’t want the additional mollies? You have several options:

1. Flush Them Down The Toilet

People think that flushing unwanted fish down the toilet is the last resort. However, this is not an option to start with. Although, people are tempted to take this step because of the convenience.

Doctor Joy Becker (the University of Sydney, Faculty of Veterinary Science) hates the concept because aquarium fish destroy domestic fish stocks by introducing deadly diseases.[5]

People rarely consider the consequences of their actions because they don’t know what happens when they flush fish down the toilet. They don’t realize that these creatures eventually make their way to local water bodies.

One study found that goldfish could travel over a hundred miles once aquarists inadvertently introduced them to local freshwater systems. Goldfish are problematic because they tend to prey on various local plants and animals.[6]

2. Leave Them In The Community Tank

As I briefly discussed earlier, rather than flushing the baby mollies, you can leave them in the community tank. Let the adults feed on them. 

Baby mollies are too small and vulnerable to escape. They are unlikely to survive the week, especially if you starve the adults for a day or two to enhance their desire to hunt and feed.

If the adults are not pursuing the babies with the kind of vigor you expect, take some of the plants and decorations away. This reduces the number of hiding spots and makes the fry much easier to find.[7]

Also Read: What Fish Will Eat Molly Fry?

3. Euthanizing Your Molly Fish Fry

Another option is to kill the fry. The creatures don’t have to suffer. You can use sedatives like clove oil that kill painlessly. The babies will die within 30 minutes.[8]

If this option doesn’t appeal to you, look for local organizations that can help you dispose of the fish. 

Some firms will play an active role in the disposal process, while others will recommend retailers and aquarists to take the babies off your hands. 

But if these organizations are unavailable, kill the fish. This solution is better than keeping the molly fry in crowded conditions. Ultimately, the stress will compel the adults to eat them. 

If the babies live alone in a nursery tank, the crowded conditions will expose them to ammonia poisoning. Either way, you can protect the babies from unnecessary suffering by euthanizing them.

This excellent video shows how to care for molly fish fry.


There are many things you can do with molly fish fry. It mainly depends on whether you wish to grow these little creatures or not.

If you do, make sure to create a conducive nursery. Adjust the tank size and water parameters, including the temperature, pH, and hardness.

If you’re dealing with unwanted molly fry, a good option would be trading them for other fish. Many fish stores are willing to do that, as it benefits them in the long run.


  1. https://www.wikihow.com/Take-Care-of-Molly-Fry
  2. https://www.petmd.com/fish/care/5-live-aquarium-plants-even-beginner-can-care
  4. https://fishkeepingguide.net/molly-fish/how-to-care-for-molly-fry-step-by-step-guide/
  5. https://www.cabi.org/animalscience/news/23561
  6. https://weather.com/science/environment/news/dont-flush-goldfish-down-toilet-return-lake
  7. https://explorefishworld.com/mollies-keep-having-babies-heres-what-to-do/
  8. https://www.wikihow.com/Dispose-of-Aquarium-Fish