When to Separate Pregnant Molly Fish?

Mollies are beautiful creatures and are aesthetically pleasing to look at. Since they are livebearers, they will eventually give birth to fry.

Finding out that your molly fish is pregnant may be both thrilling and worrisome at the same time. This is because you have to decide when to separate your pregnant molly, and parent fish don’t care about the safety of their young, heck, they even eat them right after they are born!

When one of the mollies is pregnant, they are often kept apart and this is a pretty effective approach as they require food. Most importantly, after giving birth, the mother should be kept apart from her fry since she will eat the fry.

When To Separate Pregnant Molly Fish

Fortunately, over the years of raising fish, I’ve accumulated enough knowledge to be able to tell you everything there is to know about molly’s pregnancy. This article will show you how to care for and when to separate pregnant molly fish. You should read what I learned from my experience if you own molly fish and have seen pregnancy symptoms in your mollies!

When Should I Separate my Pregnant Molly?

I will start off by addressing the main question. What is the best time to separate your pregnant molly fish?

As soon as Pregnancy is Apparent

Molly fish tend to hide most of the time when they are pregnant in order to avoid being attacked by male fish or other aggressive fish in your fish tank. As a result, some fish keepers advise you to separate your molly as soon as you detect pregnancy symptoms.

Keep a look out for these indicators as they can be crucial indicators to assist you with your fishkeeping. Molly fish pregnancy symptoms include a bloated abdomen, behavioral changes, and increased hunger.

Additionally, molly fish will use whatever means necessary to protect themselves and their young, even attacking other fish in the tank.

As soon as fish Pregnancy is Apparent

Furthermore, molly’s behavior alters, making the fish tank a hellish place for its fellow tank mates, especially if it feels threatened and has insufficient hiding places.

The increased hunger of pregnant molly fish means that they need more food, which can not only cause food scarcity in the fish tank but also force the molly to attack other fish in an effort to obtain more food, weakening those fish in the process. Therefore, it is essential to separate your molly as soon as it becomes pregnant so that it won’t experience stress and you may feed it the proper quantity without worrying about other fish.

Right Before Giving Birth

Although not recommended by me (especially if you are a newbie), some fish keepers recommend you separate pregnant molly fish right before it gives birth.

I can understand your concern: “How do I know if my molly is about to give birth?” Here are a few indications that might suggest that your fish is about to give birth in order to address that.

It will become lethargic since mollies frequently remain stationary as their due date approaches. You could also notice that your molly’s eating habits have changed. Before giving birth, she won’t eat anything and will spend her time lurking in the corners or recesses of her fish tank and skipping meals.

Right Before Giving Birth

However, The last thing your molly needs at this point is more stress, so I do not advise separating your molly fish before they give birth. Pregnancy may be extremely stressful for your molly, and moving your molly to a new tank with a different environment would just add to that stress.

Even though I do not advise it, if you move your pregnant fish to a different tank just before it gives birth, make sure the water conditions are as similar to (if not identical to) those in the main fish tank. This will lessen the stress on the fish and lessen the likelihood that your molly will suffer any harm.

After the Delivery

You must separate the molly fry as soon as they are born because it is the major objective in this situation. Some aquarists advise you to relocate the fry after they are born rather than separating the pregnant molly.

Because molly moms devour their children, it is absolutely NOT a good idea to leave the fry with its mother. The goal is to keep the fry safe.

What Should be done after the Fry is Born?

It’s time to care for the fry now that your molly has given birth. You are essentially their only chance of survival because the parents (or other fish in the aquarium) start nibbling on them as soon as they are born! Crude, huh? Nature will do that for you!

What Should Be Done After The Fry is Born

Once your molly has given birth, the most obvious thing to do is either relocate your fry to a different fish tank or move your molly back to the main fish tank. You cannot leave the mother and fry together because the mother fish will devour their fry.

The molly fry must be kept in a separate aquarium until they are large enough to not fit in the mouth of the adult fish, which takes 2 to 3 weeks.

Related Post: Pregnant Molly Fish: Behavior, Duration, Care & More

Set up a fry Tank

A fry fish tank should only contain about 20 to 30 gallons of water because, unlike a regular fish tank, it is just temporary.

Keep in mind that you will add your fry to a fry tank until they are large enough to be moved to the main tank.

Cleaning the Tank

Always rinse the tank with warm water before wiping it down with paper towels. Additionally, you should never clean the aquarium tank with detergents, soap, or any other chemically manufactured goods. Different chemicals included in soap and detergents are hazardous to the health of newborn fish.

Cleaning the fish Tank

Add Gravel Etc

The substrate, such as gravel, aquarium rocks, or sand, offers more beauty and a place to hide in the aquarium. You must undoubtedly rinse the substrate with warm water and a colander before adding it. Moving the substrate around requires caution because it runs the risk of scratching your aquarium tank.

Add Gravel in fish tank


The tap is the primary source of water in any house. You must use a de-chlorinator to purify the water before adding it to the tank since tap water includes chlorine and other chemicals that are extremely damaging to young fish. You must add purified water instead of tap water if you don’t want your newborn fish to suffer or perish.

Adding Essentials

The time has arrived to select the aquarium’s necessary equipment. For the fry tank, all you require is a nice sponge filter, an air pump, and a heater. Keep the fry tank as uncomplicated as you can; you don’t need any expensive equipment.

Adding Essentials in fish tank

Nitrogen Cycle

The biological filter, where nitrifier bacteria will proliferate, can now be added. The harmful nitrite and ammonia are removed from the tank by the bacteria in the biological media.

Nitrogen Cycle

You must use an ammonia-based mixture designed specifically for aquariums for this. Numerous factors determine how long a ride will last. To ascertain whether the biofilter has successfully stabilized, carry out the water tests once a week during the process. It will take about 8 weeks to complete this process.

Add the Fry

Once you are done with everything you may add the fry Introduce the fry when the fish has gotten used to the water. Put your fry in a container, then float it on the new tank. Allow the water to adjust to the temperature for 15 minutes. Once the temperature seems to have stabilized, use a cup to help you add water from the tank to the bucket.

betta fry

Make sure the transport water is at least six times as diluted as the tank water by adding a quarter cup of tank water to the bucket every minute. It is now safe to take each juvenile fish out of the bucket and place it into the tank one at a time using an aquarium net. It’s important to keep in mind nevertheless that you shouldn’t fill the bucket with sewage.

The Bottom Line on When to Separate Pregnant Molly Fish?

Mollies should be separated from the fish tank as soon as they get pregnant. This is because mollies can not only make life hell for every tank mate around them during pregnancy, but it is also easier to take care of the fry once as separating the mother from her fry will be enough for the survival of the offspring!

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