Home Aquariums Molly Fish Giving Birth Signs (What To Look For)

Molly Fish Giving Birth Signs (What To Look For)

by Lucy

Mollies are relatively easy fish to care for, and once you have mastered caring for mollies, you might want to start breeding them.

Breeding mollies in itself isn’t too hard, and they do breed quite well. However, to provide the best care for your pregnant molly fish, and to ensure that the fry are looked after, you would need to know the signs to look for that she is about to give birth.

What are the signs to look for that a molly fish is giving birth? There are a few signs that indicate that a molly fish is about to give birth. Pregnant mollies develop a square bulging stomach and an opaque gravid spot. They will act more timid, and they will stop eating as much.

Being able to recognize the signs that a molly fish is about to give birth will allow you to prepare her environment for the arrival of the fry, to give her and her babies the best chance at survival!

Below are all the signs to look for that a molly fish is going to give birth, and some other helpful information.

How Do I Know A Molly Fish Is Pregnant?

Before looking for signs that your molly fish is about to give birth, it helps to know the signs to look for that she is pregnant.

Most mollies look visibly pregnant, but this can take some time and you might not notice this early enough. If you are wanting to breed mollies, then understanding their gestation and pregnancy signs is really important, and can help you breed them successfully.

Female mollies are ready to breed at around 6 months of age, and if they are around males, there is a good chance they will breed. Molly fish are livebearers and will give birth to live fish.

These are the signs to look for that a molly fish is pregnant:

Growing Belly

A pregnant molly fish will have a bigger belly than normal. As the belly grows, it will eventually square off, which is different from the normal round bellies that mollies usually have.

Not only will her belly begin to square off, but it will become noticeably thicker too. By the end of the gestation period, right before she gives birth, her belly will be noticeably large.

Increased Appetite

Growing babies take a lot of energy, and because of this, a pregnant molly will have an increased appetite. This might not be so easy to monitor, but if you generally watch and keep track of how much your molly fish eat, you could pick up on this. It does help to look for other signs too.

Black Lines On Belly

Lighter color mollies have a tell-tale sign when they are pregnant – they develop a black line on their belly. They might also develop darker black spots too. Darker mollies can also develop these lines and spots, but they might be harder to notice.

Signs A Molly Fish Is About To Give Birth

The first step is to know the signs to look for that indicate that a molly fish is pregnant. Next, you would need to be aware of what to look for that indicates that the molly fish is about to give birth.

If you know that your molly fish is pregnant, it is really important to keep a close check on them for signs that she is about to give birth, so you can properly prepare her environment to be safe and comfortable, as well as suitable, for her when she does give birth, and for her fry.

These are some of the signs to look for that a molly fish is about to give birth:

Squared Belly

One of the biggest giveaways that a female molly is about to give birth is when her belly becomes very squared off. Noticing a larger belly is a sign that a molly fish is pregnant, but when it becomes very pronounced and with a square edge, she is likely to be close to birth.

The closer the molly fish is to the due date, the more square the outline of her belly will be. You might even notice a very subtle V-shape at the bottom of her belly. 

A very squared-off belly means that your molly fish is very close to giving birth, and you should start preparations for the fry to arrive.

Opaque Gravid Spot

A gravid spot is unique to livebearer fish. It is a spot found near the anal tail, and it appears when a fish is pregnant. Molly fish do display this gravid spot, and it is a way for breeders to monitor the pregnancy.

As the molly fish is pregnant, the spot becomes darker and darker. As it becomes darker, the gravid spot also becomes opaque, and when the molly fish is close to giving birth, the spot will be completely opaque.

Some breeders can even pick up very slight movement in this area – which are the eyes of the fry moving around. 

Decreased Appetite

A pregnant molly fish will have an increased appetite, to make up for the extra energy her body is using to grow the fry. However, when it comes time to give birth, her appetite will decrease.

The pregnant molly will either reduce the quantities they consume or ignore the food in their tank completely. 

Do not become too concerned if your pregnant molly suddenly stops eating, because if she displays some of the other signs that birth is near, it just shows that the date is nearing and you should prepare her for the fry to arrive.

Reclusive Behavior

Close to giving birth, a pregnant molly will become reclusive. You may have noticed that the pregnant molly was a little more aggressive during pregnancy, but as the date nears, she will withdraw and spend more time hidden away in dark corners in the tank.

Finding decent, secluded and safe hiding places makes a molly fish feel safe when nearing birth. Without these safe spots, she can become stressed and feel insecure leading up to the birth. 

As she is pregnant, she will become more sluggish as well and will need the protection of dark spots and plants to keep her safe. Make sure that you have provided ample spots for her to hide in, away from other fish, and just to make her feel more comfortable.

Tail Shaking

One of the stranger signs that a molly fish is about to give birth is that she will shake her tail more when swimming. 

Tail shaking is actually considered to be a sign that a molly fish is stressed, and if a normal fish who is not pregnant shakes their tail, it could indicate that there is something wrong in their environment, such as the water acidity being too high.

A pregnant molly fish shaking her tail or shivering more when she swims indicates that she is likely stressed, which means she is close to giving birth.

How Many Fry Do Molly Fish Give Birth To?

How many fry a molly fish can give birth to does depend on the fish herself, and also her age. A molly fish who is pregnant for the first few times will usually give birth to a smaller number of fry, whereas an older molly fish who has been through numerous pregnancies will give birth to a larger number of fry.

Molly fish can give birth to between 40-100 fry in one pregnancy, which is quite a lot of new fish to have!

Their gestation period lasts for around 60 days, and you should be able to notice that they are pregnant at some point by the different signs that they display.

Do I Need To Move A Pregnant Molly Fish?

Whether or not you want to separate a pregnant molly is completely up to you, and whether or not you are actively trying to breed your molly fish.

If you leave the pregnant molly fish in the tank along with the other fish, and if she has a dark, secluded space to go to, she will give birth. However, because her fry would be so small, the other fish in the tank will likely eat them, and there is very little chance that the fry will survive in a tank with lots of other fish.

For when you are actively trying to breed molly fish, it is a good idea to move her to a separate tank, and make sure that this tank is suitable for what she needs.

Here is what to do when you want to ensure that as many fry survive as possible:

Move The Pregnant Molly

It is a good idea to move the pregnant molly to a separate tank for the rest of her pregnancy, and for her to give birth in. Take water from the original tank and place it into the new tank, making sure to add in some hiding spots for her to feel safe in.

The tank will also require a filter, but you need to make sure to place something porous over the opening of the filter, as the fry are small enough to be sucked up into the filter. A heater can also help to keep the water at the right temperature for the fry, at around 72-78°F.

Once the molly fish has given birth, you should move her back to the original tank as she might eat her own fry.

Use A Breeder Net

If you do not have another tank to use, you could use a breeder net in the main tank. The breeder net helps the fry become separated from the other fish while keeping them in the same tank.

The problem is that breeder nets can often stress out the mom.

Keep Fry Separate

You do need to keep the fry separate from other fish to prevent them from being eaten. The fry should be kept separate from the other fish for at least 2 weeks.

After 2 weeks, the fry are large enough to be placed back into the main tank with the other fish, as they are not too small to be eaten by the other fish.

Does A Pregnant Molly Fish Require Special Care?

There isn’t much special care that a pregnant molly fish needs while they are pregnant, but you can help them out as they get closer to birth.

It does help to give your molly fish a comfortable, stress-free environment when pregnant, to help her reach full term with her fry.

These are some things you can do to help your pregnant molly fish:

  • Provide extra hiding spaces and shelters for your molly fish to hide out in. As they get further along in their pregnancy, they will spend more time in darker spaces where they feel safe. The more spaces they have to hide out, the less stressed they will feel.
  • Adjust the water temperature to be a little bit warmer, around 72-78°F. This warmer temperature will help her relax a little bit more and feel more comfortable, reducing the chance of the pregnancy failing.

If you cannot make these changes in the molly’s tank, then you might have to move them through to their very own tank. This will give them time away from other fish that could stress her out, and allows you to better adjust the tank to the environment that would suit her best.

It also allows you to raise the temperature of the tank without stressing out the other fish in the tank and makes it easier to separate the fry when they are born, keeping them safe too.

Do I Need To Feed The Fry?

You will need to feed the fry when they are born. The mother will not care for the fry, and she does need to be moved away from them and into a separate tank to prevent her from eating them.

You don’t necessarily need special food for the fry, you can just grind down the adult mollies food and feed it to them. Without grinding the food down, the flakes would be too big and the fry would not be able to fit the food in their mouth.

Final Thoughts

There are some signs to look for that indicate that a molly fish is about to give birth. Her belly will grow and begin to square off, her gravid spot will turn opaque, she will eat less, and she will hide away in dark corners more.

It also helps to know the signs to look for that a molly fish is pregnant, so you can start preparing for the birth and the arrival of the fry.

Keep a check on your pregnant molly fish, and look for signs that she is close to giving birth, so you can ensure she is kept as comfortable as possible, and that you are able to look after the fry as best as you can.

How long is a molly fish in labor?

How long a molly fish is in labor for does vary. Labor can last from 1-24 hours, and it also depends on the environment that the molly fish is in.

Will a mother molly fish eat her own babies?

A mother molly fish can eat her own babies, and cannibalism is a normal trait among molly fish. This is why it is important to move fry away from adult fish, including their mother if you want them to survive and not just become fish food.

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