How to Tell If a Molly Fish is Pregnant

Do you have a female molly fish in your tank or pond? Are you wondering if she is pregnant? Do you know the signs that will tell if she is pregnant? This article will discuss how you can tell if your molly is pregnant.

Unlike most fish, mollies are livebearers, meaning they give birth to their young ones alive. When a molly is pregnant, you will notice some physical change like protruded stomach, having a dark triangular spot near the anal vent, etc. You will also notice behavioral changes as the molly will stay away from other fish in the water and move slowly.

Signs Your Molly is Pregnant

Your molly is not human, so you should not expect it to walk up to you and tell you it’s pregnant. However, you have to look out for changes, both behavioral and physical changes, before you can tell if it is pregnant. These signs will give you enough knowledge of the condition of your fish.

If you want to tell if your molly is pregnant, you have to look out for two kinds of signs; behavioral and physical signs. Behavioral signs include activities and reactions to its environment, while the physical signs entail its body change and appearance. Here are signs to look out for in your mollies;

  • Slow movement: This sign is a common behavioral sign that tells your fish is pregnant. You will notice the molly swimming slowly in the water. You have to be sure of this sign as it can also be a symptom of diseases and illness.
  • Seclusion: You will also notice the female molly secluding herself from other fish in the water. This behavioral sign is obvious as you will see the fish move far away from other fish, resting and looking for calm and cool locations.
  • Protruded stomach: This sign is a common physical sign in most pregnant fish. You will see your molly’s stomach becoming bigger as the babies mature in her. You will notice her stomach stretching out and becoming bigger.
  • Dark spot: You will also notice the appearance of dark spots near her anal vent. The triangular dark spot becomes darker and more obvious as the pregnancy approaches the ripe stage.

Once you start noticing these signs, you should start preparing for her fries’ arrival. You have to ensure she gets adequate requirements and conditions.

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How Long Are Molly Fish Pregnant For

Mollies are one of the few fish that give birth to their young ones alive. They can carry their young ones for about 6 to 10 weeks, i.e., mollies can be pregnant for six to ten weeks. In addition to this, as their pregnancy period counts, their behavior and physical appearance begin to show they have company in them.

Mollies are a type of guppy as they are of the same genus but different species. Mollies can carry 20 to 100 young ones during pregnancy and give birth. In addition to this, they also breed frequently, making them discharge as many offspring much as they can.

During the pregnancy period, you have to make sure your molly is in good condition. You also have to provide adequate water and tank conditions to ensure her good health. Sometimes, it is best to remove the expectant mother and keep her separately in another tank for special attention and safety.

How to Tell If your Molly Fish is about to Give Birth

The previous signs also start to become more visible. When you start noticing this, you will know her delivery date is near. When your molly fish is about to give birth, you will notice the stomach to be unmistakably large.

The babies in her are now larger and more ready to see the world, causing her stomach to expand to accommodate their growing size. Her stomach’s size will show how much she is ready to let her babies out.

You will also start to see her gravid becoming more obvious. The dark triangular spot near her anal vent becomes much larger and darker than before. In addition to this, the molly’s peritoneal wall begins to stretch, causing the dark spot to stretch and increase.

You will also notice the eyes of the fry becoming visible. It is not always visible, but you will sometimes see the young ones’ eyes through the thin walls of the molly’s gravid spot. You can also notice the fry’s body from the walls of her stomach.

Your molly will also develop a bulge below her gills as the delivery date becomes nearer. You will also notice your molly’s outline becoming fairly square. She starts finding it difficult to swim around in the water at this stage.

When you start seeing these signs, you should remove your pregnant molly from the tank and place her in another. It will save her and her fries from impending danger from other fish and other factors. It will also enable you to pay special attention to the female molly and her fries.

How Mollies Act Before Giving Birth

Your molly fish will show you signs that it wants to give birth. It is now left to you to notice these signs and take necessary actions. Your molly will keep showing signs, even till the last minute before its delivery.

Mollies can sometimes act funny when they are about to give birth. One of the things you will notice is they will start acting restless. You will tell from their behavior as they will try getting a comfortable position in the tank.

You will also notice them secluding themselves from other fish in the tank. They will leave their tankmates and settle in a calmer and cooler water location. You will also notice the fish preparing places in the tank for their new kids’ arrival.

The molly can also show a bit of aggressiveness when ready to give birth. You will also notice she does not swim much. She will stick to a position for a longer time than she normally does.

How Long Does it Take for a Molly to Give birth?

Molly will give birth right after they complete their gestation period. The gestation period in molly fish can last about 6 to 10 weeks. In rare cases, the gestation period may exceed ten weeks, most unlikely to occur.

After the gestation period elapses, the molly will give birth to her young ones. Before a molly can go into gestation, she has to become mature. Furthermore, male mollies will become matured and ready for reproduction when they reach 12 months.

Female mollies usually attain maturity at half the age of males, so they will be ready for pregnancy when they reach six months. So, it will take about nine months for your molly to give birth. This nine-month count starts from her birth.

Mollies can carry about 20 to 100 fries in them during pregnancy. They also breed more frequently, making them suitable for you to keep for breeding purposes. In addition to this, mollies will breed as soon as their young ones become mature, continuing the reproduction cycle repeatedly.

Do Mollies Eat Their Babies

Like many livebearers, cannibalism is normal with mollies. They tend to eat smaller and weaker fish, regardless of the species. Mollies will definitely eat their babies when they get the chance.

Mollies do not lay eggs but give birth to their young ones alive. However, when mollies give birth to their young, the small fish are usually weak and fragile, making them prone to attack from other fish and even their mothers. You might also need to take the necessary actions if you want to keep your small mollies alive and safe.

Since the fries are weaker and smaller than other mollies, they serve as easy meals. You might need to remove the fries and keep them in another tank for their safety. You will also need to cater to them separately to ensure their wellbeing.

Tips to Save Molly Fry

You need to save your molly fry from adult mollies and other fish in the tank. If you do not protect them, you might lose them to other fish in the tank as food. Here are some simple tips for you to save your molly fry;

  • Set up a separate tank: One of the best ways to save your molly fry is to set up a separate tank for them. Setting up a separate tank will help you keep out fish that will eat your molly fry. It will also enable you to provide the needed and adequate requirements.
  • Set up a breeding box: One of the easiest ways of keeping your molly fry safe is to set up a breeding box in the main tank. It will save you the stress of setting up a separate tank for them. The breeding box will provide the molly fry with what they need and save them from other fish.
  • Add plants and structures :If you do not have the means to set a separate tank or use a breeding box, you have much work. You will need to add plants and structures to the tank to create a hiding space. Although this might not be very effective, it will do a good job of saving them.
  • Set up filter system: Molly fry are small and fragile, so you need to provide them with what they need. You have to set up a filter system for them. The filter system will ensure they have a healthy and safe aquatic environment.
  • Feed them adequately: Food is necessary for your molly fry. You have to make sure you give them the right food and at the right time.

How Long Do I Need to Separate My Baby Mollies?

You have to separate your baby mollies from the main aquarium until they are large enough not to fit into the mouth of other fish. You can keep the mollies in a separate tank for about 4 to 6 weeks. By this time, the baby mollies should have grown large enough for the adult tank.

You have to be sure the adult mollies will not be able to eat the baby mollies before adding them to the tank. In addition to this, if you are using a breeder, you will also have to be sure they are of the right size before returning them to the tank. When the fish are about eight weeks old, they will fit the adult tank.

What to Feed Baby Molly Fish?

Your baby molly fish needs to eat for it to grow into the adult stage. You have to make sure you feed it with the right food to ensure its growth and development. One of the foods you can give your molly baby fish is fish flakes.

Baby molly fish will eat fish flakes when you give them to them. You have to make sure you crush the flakes into a fine texture for the fish to eat them easily. Crushed fish flakes will provide your baby fish with the needed nutrients.

You can also feed them baby brine shrimps. Your baby molly fish will eat baby brine shrimps as long as they can fit into its mouth. Brine shrimps are highly nutritious and beneficial to baby molly fish.

You can also feed them with little plants and algae to aid their rapid growth and development. Your baby mollies will grow as much as you feed them. If you feed your baby mollies well, they will be of large sizes in eight weeks.

You will even be able to add them to the large tank by then. The baby mollies will be large enough to eat the same food as other adult mollies. They will also be free and safe from attack from adult mollies and other fish.


You can tell if your molly is pregnant by looking out for some signs she will exhibit. When your molly is pregnant, it will definitely exhibit obvious behavioral and physical changes. When you notice these signs, you should know your molly is full of babies.