How Long are Molly Fish Pregnant For?

Keeping fish is a rewarding and relatively easy hobby. Fish require minimal attention, and are perfect little additions to our homes or ponds. Over 12 million households in the US alone keep fish as pets. 

If you have your own little fishy friends, it is vital that you are aware of some important factors to keep your fish happy. 

Despite their quiet and calm nature, we can grow incredibly attached to our fishy companions, and love to watch them grow and swim around their aquariums. Some fish owners even breed their fish, and molly fish are great for this purpose.

Mollies are some of the most popular and widely available tropical fish in the world. Mollies are often very peaceful fish that coincide with many other different types of fish. They are often found pregnant or bought pregnant from a pet store.

For this reason, molly fish are perfect for breeding, but as with caring for any fish there are a few conditions you should consider in order to create the perfect environment for pregnant fish. 

All fish should have a properly cared for and maintained living environment. Their aquarium should have enough space for the capacity of fish, and it must be free of any toxins or contaminants.

All fish produce waste that must be properly disposed of. Fish aquariums should have a properly functioning water filtration system in order to maintain the health and wellbeing of your fish. When a fish has a well-cared for living space, it can be the perfect environment to breed them. 

Female molly fish can hold and store male molly sperm, and ultimately impregnante themselves. This surprisingly, can be done every 30 days! However, the general length of a molly fish pregnancy is 60 days. 

How do molly fish become pregnant?

Molly fish breed by the process of internal fertilization. 

Male molly fish will inseminate the eggs, whilst the female molly will maintain and store the eggs. Female molly fish can store male molly fish sperm for many months, and can then impregnante themselves every 30 days with their stored sperm. 

The typical gestation period for molly fish is around 60 days long. In addition, some female molly fish can give birth to anything from 20 up to 100 live fish babies at once. 

Molly fish are most often pregnant throughout their lives, so it is important that you know how to properly care for your molly fish and their babies.

How to tell if your molly fish is pregnant?

There are a few ways to determine whether your molly fish has become pregnant. 

Try to examine or look at your fish daily for any well being changes of signs of illhealth. The most obvious sign to look out for is the swollen belly. If you notice any changes in the shape of your female molly fish then she may be displaying signs of pregnancy.

Another notable signal that your molly fish may be pregnant is that she will be far less active than normal. She will eat much more and isolate herself from the other fish. A pregnant female molly may also spend more time near the heater or act in a different manner. 

A pregnant molly fish may hide frequently and only surface for food. She may be a little more aggressie towards other fish in the aquarium, and try to stay away from them. It would be beneficial to your molly fish to provide her with plenty of plants or decorations in the tank so that she has spaces to hide. Molly fish require that comfortable and secure feeling of being tucked away so that they can give birth peacefully.

The final way to tell whether your molly fish is pregnant is to find a dark triangular spot near the female’s anal vent. This is the gravid spot. It can be very dark or almost black in color, so will be hard to identify on a black molly fish. 

However, this spot should enlarge as the pregnancy progresses. If it is particularly large and visible to the eye, then this may be a sign that your molly fish is about to give birth. 

Caring for a Pregnant Molly Fish

We recommend that you try to separate the pregnant molly fish from the others when she is about to give birth. This way she has her own space and will not be stressed out by the other fish. 

We also separate mother and baby fish from the others as fish often eat their young. As mollies create live young, they need extra help for survival. 

We would recommend that you purchase a breeder box prior to the molly fish giving birth. A breeder box is a small cage that resides on top of your tank. When your female molly is ready to give birth, you can place her within this small cage and keep her separated from the rest of the fish. 

Alternatively, you may want to use a net to remove the female pregnant molly from the tank once she has dropped the babies to avoid her consuming them. Once the small fry is large enough to defend itself then they can be reintroduced to the aquarium. 

Pregnancy Tips

Having a pregnant molly fish is very exciting and can be a challenging time. It is crucial that you are aware of proper molly fish care and can therefore provide the best living environment and safety protocols for the health of your fish.  

The main things to remember are:

  • You must keep an eye on your fish as best as you can.
  • Look for any changes in behaviour, or signs of illhealth. 
  • You should also maintain a safe living environment for your fish. 
  • Remember that molly fish have a gestation period of up to 60 days.
  • Separate your female fish from the fry fish in order to give them the best chance of survival.