Molly Fry Care Guide (3 Main Things to Do)

This entry is part 5 of 5 in the series Molly fish

As in the previous post, you all know molly fish is a very productive fish. The mother fish is capable of producing 20-60 fries in a single spawning.

However, if we just leave the fries in the tank with the other adults, there isn’t much hope that the fries have a chance of surviving to grow up to adulthood. The reason for this is because adult fish, even the mother, will eat the fries before they can grow up.

You want to save the fries and give them the best environment for growth. This article is for you. So how do you take care of baby molly fish?

The care for baby molly fish can be summarized in the following three main things:

  • Isolate the mother fish from other fish before giving birth
  • Create a suitable environment for the fries
  • Feed the fries

Also, this article answers questions that are often asked by molly fish owners.

Let’s get started.

Molly fry care guide

In order for you to ensure that your molly fries are staying alive and growing to adulthood, these are the most important three things for your molly fry care guide.

1-Isolate the mother fish

It is important to know that you need to isolate the mother from the other fish before she is giving birth.

Our previous post did give you advice on how to know that your molly fish is about to give birth. When you aren’t going to isolate the mother, the other fish is going to eat the fries as they are born.

By isolating the mother, you will also make sure that the mother isn’t stressed during birth, which can cause you to lose fries as well.

There are three ways to isolate her so that she can give birth to the fries, and that you can rescue as many of the fries as possible. With the three different ways, you can choose the one that is best for you.

  • Adding plants and hideaways in the main tank.

The first option is to add more plants, artificial plants, and hideaways in the main tank. Giving the fries hiding spots when they are born and for the first couple of weeks. This might be the easiest solution, but not the most recommended one.

With this method, you are going to lose fries. Sometimes you might just lose one or two. But, most of the time you can lose more than half of your fries. This isn’t the most effective way to care and raise your molly fries. Especially if you have lots of adult fish in the tank.

  • Placing the pregnant molly in a separated tank

This is an option that many are considering. Having a completely separated tank for the pregnant molly fish. Giving her, her own tank where she can give birth safely.

The fries will also be safer than with the first option. However, you need to remove the mother molly the moment that she is done giving birth. She will still eat her babies if you don’t remove her quickly.

You should also make sure that the water in the birth tank is the same as in the main tank. Otherwise, the pregnant molly might get sick and lose the fries even before she can give birth.

It’s a better option but you need to spend money on a separated tank and other things like filter, heater, and air pump.

>> Learn more about how to choose filter for your tank.

  • Installing a breeding box in the main tank.

This is the most affordable option to ensure that you don’t lose any of your molly fries. To install a box into the main tank that is designed for the breeding.

It is normally a plastic mesh or container that is getting installed in the main tank. The water is still able to run through the breeding box, without any fish getting into the mesh. Protecting the mother’s molly and the fries.

After giving birth, you are removing the mother, placing her back into the main tank. Giving the fries some time to grow larger before replacing them in the tank as well.

2-Create a suitable environment for the fries

No matter how you isolate the mother fish, you should create the best environment for the fries to grow.

So, what are the factors that make up a suitable environment for fry growth? We will discuss these factors further. So, stay with us…

Tank and filter system setup

To care for your molly fish correctly, you need to have the perfect tank and filter system setup. The fries are delicate and need to have the right set up to grow to adult size. These are everything you need to make sure about when it comes to the tank and filter system setup for molly fries.

  • Find a tank that is large enough

You should look for a tank between 5 and 20 gallons to raise fries. When you intend to keep the mother with the fries, or when you have multiple broods going into the same tank, then you should consider getting a larger tank.

If your fry is going to be born alive, then you need to make sure that the nursery tank is ready. Before the mother is giving birth, to be able to put the fry in just after birth.

  • Setting up the filtration system

Having a good filtration system is important to any tank. But it is especially important for your molly fries. It’s recommended that you are setting up a simple foam filter, or any other similar filtration system for the size of your tank. You need to make sure that the filtration system is fry-safe and that it can’t get sucked up. You can purchase an attachment or fitting from your local aquarium store to make the filtration system safe.

Or, you can make your filtration modification to ensure the safety of your fish. You can cover the filter with a sponge or foam to make the filter safe for the fries.

>> Further Reading: If you’re looking for more great filters consider checking out our review and guide on the filter system series


With the water, the important thing to remember is that you need to know how to do a water change of molly fry tanks. Here is how to do water change:

  • Even if you have a filtration system, you need to change the water regularly to ensure the health of your fries. It is recommended that you are using some water from your standard tank to add to your fry’s water.  This is to acclimate them to their home eventually. To have the same water, will make it easier to add them to the main tank when they are ready.
  • You might want to consider a 20% water change every day to your fry tank. For example, if you have a 10-gallon tank, you might want to take 2 gallons out per day and replacing it with water from your main tank. Don’t use regular tap water for the replacement.


The right temperature for your mollies is essential. This is why you need to heat your tank because they are tropical fish. They will need to have a water temperature between 72 and 84 degrees Fahrenheit (23 to 28 C) to be as close to their natural habitat as normal. You can get this temperature by using an aquarium heater.

>> Explore the most affordable heater for mini tank on Amazon.

You should also make use of an aquarium thermometer to monitor the temperature to ensure that the water is at the right temperature, at all times.

>> Explore the top rated aquarium thermometer on Amazon for mini tank

Add plants to your tank

You can use artificial plants, or even live plants. But, it’s important to plant them into your tank before the fries arrive. The plants provide hiding spots for the fries in their first days of life, and it acts similarly to a breeding trap.

You should look for a mix of broad-leafed plants, like Java ferns and grass. This is the best way to create hideouts for your fries. Some float plants are also essential. This assists the newborns to have an area near the surface to hide immediately after being born.


You should make sure that there is a balance between light and darkness for the fries. It is recommended that you should offer only 8 hours of light each day. The rest of the day should be devoted to darkness for rest. The right lighting conditions will ensure that the fries are developing healthy and into adulthood.

Feeding the fries

The moment that the fries are born, you should feed them. There is food that is made especially for molly fries that you can find at your local aquarium shop.

If you don’t have any fried food, you can always use baby brine shrimp or high-quality flake that is ground into a fine powder. Remember they are small and need really small food.

What kind of foods should we feed them?

The normal flake food that you are giving your mollies is too large for the fries. To make it easier for them to consume, you can use a coffee grinder or a mortar and pestle to grind up the fish food into a fine powder.

If you want to make sure that you are giving your fries the best, then you should consider Hikari Fish Food. This fish food is designed for feeding all tropical and marine fish. These are rich in protein to ensure rapid and healthy growth.

Live food is also a great food choice for small fries. You can go for baby brine shrimp, vinegar eels, daphnia, or micro worms. These foods can be frozen or free-dried as well if you can find live ones.

Something else that you can give your fries that is protein-rich is hard-boiled egg yolk. You should make it into a paste and can be stored in the fridge. This is a cheap option but gives the necessary protein to the molly fries.

How should we feed them?

It is important to keep a regular feeding schedule. You should feed your fries small amounts of food, several times a day. It should be about a pinch at a time. To remember the schedule, feed the fries before or after you have eaten a meal.

When you are keeping your fries in the same tank as the adults, you can give them the same food as the adults. You should just crush the food so that it will fit into their mouths. The finer the food for the fries, the better.

Remember that molly fries are tiny and their mouths aren’t much bigger. You will need to procure food that is appropriate for their size and that will fit into their mouths.

It is important to make sure that you don’t over-feeding them and that you scoop all the left-over food out.

Attention when feeding them

After the fries have eaten, you should clean out any uneaten food from the tank. To do this, you can use a net or skimmer to remove the powered food from the surface of the water. This can make the water filthy if you have uneaten food in the tank.

Just like any other fish, you can still overfeed fries. So, you should manage the amount of food you are giving at a time. And, you need to scoop out all the access food that the fries didn’t consume.

You should make sure that you consider the size of the fries, and their mouths when you are feeding them. This is why you should ground the flakes into a powder before feeding it to them.

Keeping a regular feeding schedule is important for the free to grow into healthy adults.


How fast does Molly Fry grow?

It takes about one to two months for your fry to grow large enough to go into your main tank. It is important to remember that the fries should be larger than the mouths of an adult molly fish before you add them to the main tank. You should not move them into the main tank until you are sure that they can handle it

What color will my Molly Fry be?

Molly fries can be any color they want to be. Normally, they are close to the colors of the parents. Fries are dark grey but as they are growing and getting older, they will start changing color. And, before you know it, you have a colorful tank full of mollies.

Does Molly fry need an air pump?

Yes, molly fry needs an air pump. They do need something that is breaking the water surface for gas exchange. This is so that they have the right oxygen levels required to stay alive. You just need to make sure that you are installing the right type of air pump and filter into the tank.

>> Related post:

How Long Can Fish Survive Without an Air Pump? | A Guide to Air Pumps

When can I put my Molly Fry in the tank?

You can put the fry in the tank for about 2 weeks. This is when molly fries are large enough to not be mistaken for food anymore. They can then be released in the main tank, or you can put them into their own, separated tank.

What fish will eat Molly Fry?

Molly adults are large enough to eat their fries. They can eat it for a couple of months. However, other livebearers can also eat molly fries. These fish are swordtails and Platies. Platies might be smaller, but they will be able to eat fries until they became too large to consume.

Can I keep molly fries in a bowl?

No, you can’t keep molly fries in a bowl. There isn’t enough filtration and hiding spots for fries. You will not be able to place a heater in a bowl, that is normally made from plastic. Molly fish are tropical fish and need warm water, generated by a thermometer.  

How big is molly fish fry at birth

Molly fries are smaller than the mouths of an adult molly. This is why you should keep them apart from the adults for the first couple of weeks. The smaller the female molly, the smaller the fry will be.

How to tell male and female molly fry apart

Male mollies are more torpedo-shaped and have longer fins than females. Their colors are also more intense than females. The females are wider than the males, her fins are shorter, and her anal fins are rectangular.


Now, you know everything about caring for your molly fries. From separating the mother fish from the rest of the fish to preparing the right environment for fries. The most important part of caring for fries is the feeding process. You need to know how often and how much food you need to give your mollie fries.

This is making sure that if you have molly fries, that you can take care of them, successfully.

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