At What Stage Do You Put Baby Mollies Back In The Tank?

Baby mollies need protection from adult fish. Placing them in a breeding box is the most ideal way to keep them safe and secure their growth before you put them back in the tank. You can put baby mollies back in the tank at about two weeks. When you place your baby mollies in a breeding box, do not keep them there for over two weeks, as this will also stunt their growth. 

If you are setting a fish tank for your mollies, here are the things you need to consider

Tank Size And Filtration System

10 to 20-gallon tank size can accommodate a number of molly babies, but you can also change the size depending on how many you will really place in the tank. Pick a filter that is also safe for the baby mollies, and this will also ensure that the water is clean and free from any element that may be harmful to growing mollies. 

Adding some plants can be your option, as the plants have a natural filtering capability. 

Ideal Temperature

The maximum temperature in the tank is up to 80 degrees Fahrenheit. Warm water can make the mollies eat more because it speeds up their metabolism. You may opt for a heater to keep the temperature in the tank perfect. 

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You can use an aquarium thermometer to check the water temperature, so it will remain consistent throughout. 

For every gallon that you will add just add 5 watts to get the ideal temperature or if you want to have a perfect temperature, you may also ask the help of the aquarium specialist in your area.

Water Quality

The quality of water should be the perfect environment for your baby mollies with less the toxins. You may need to frequently change the water where at least half the tank is removed to be replaced with fresh water. This is also true when you have many baby mollies and will cloud the water faster. If you have just a few baby mollies, though, you can change the water once a week. 

Adding Plants

Make sure that you plant your tank before you place your baby mollies, so they have cover to use and they can get used to having plants in the tank earlier. 

Broad leaf plants such as Java ferns and grasses are ideal plants for your tank. You can also mix some floating plants in there as a hiding area for your baby mollies. 

Breeding Trap

Mesh boxes can be used to protect your baby mollies where you can hang them on the side of the tank. 

This is required if you are going to place your baby mollies with other small fish. 


Get the right food material from your local aquarium shop cause they will have quality food meant for baby mollies. Another option is to give them baby brine shrimp or any flake food that is high quality and should be grounded before feeding them to your mollies. Ensure that you have powder the flakes first cause they will be too large for your young mollies. 

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Feed them a small amount, just a pinch at a time for several times a day. Remove the leftover food from the tank by using a net. It is easy to see this leftover food cause it will be on the water surface. 

Watch out for overfeeding cause even if baby mollies will feed every half an hour, feeding them at least five times a day is ideal. 


You can offer your baby mollies at least 12 to 16 hours of light every day and let them rest in the dark for at least 8 hours. Having a good lighting condition is healthy for their development. 

Need To Change The Water

Although there is a filter in place, it still requires you to change the water to ensure that your baby mollies will have a clean and healthy environment. Change just 20 percent of the water from day-to-day, but not fully changing the whole tank. 

What Will Cause Baby Mollies To Not Thrive In The Tank?

Placing them back in the tank before they are ready. You should phase out and make sure that you wait for at least two weeks before placing them back in the tank. By that time, they can be acclimatized to the water, and they are large enough to go with other fish. 

Unfit water condition

The water in your tank may be the culprit if you notice your baby mollies not swimming as they should and just staying under the tank. This is not a good sign of a healthy fish, and you should check what is ailing them. 

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Too much feeding

You may feed them more than you should. Space the feeding, so they can have time to digest the food and will not be overfed. 

The culprit may be the food you are feeding them cause incorrect food may also affect their growth.

Leaving excess food in the tank to rot and increase the level of ammonia in the tank may also cause death to your baby mollies. 


Fish can become a victim of stress, just like humans. They also get low immunity to diseases, which can cause death at a fast pace. Loud noise, changes in the water quality, hands tapping the tank, or dipping inside the tank can disturb them can contribute to their stress. 

Baby mollies are still at their most sensitive phase and refrain from giving them any disturbance that may cause them to weaken.

Overcrowded Tank

You may not know it, but you may be overcrowding your fish tank. This may be the reason your baby mollies die one by one. This is true, especially for those who just started with the hobby of growing fish and may not have the idea of the space that is required for correct breeding. 

When the fish cannot move around, there is also an increase in ammonia in the tank, and this is what you should avoid. If you have a little idea on how to go about the measurement, you can ask for help from your local aquarium seller so you will be guided. 

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