Balloon Belly Molly Care

balloon belly molly

Last updated on August 8th, 2022 at 10:39 am

The balloon belly molly fish, also known as balloon molly fish, or Poecilia sphenops, is a freshwater fish found in the rivers of Central America and Mexico. This fish can grow up to 3 inches long and can live up to 5 years in captivity when well cared for and kept in an aquarium with proper environmental conditions.

When you’re looking to bring some beautiful, unique fish into your home aquarium, the balloon belly molly fish (Poecilia sphenops) can be a great choice. They’re relatively easy to care for and come in stunning colors that will make your tank look amazing as they swim from corner to corner at all hours of the day, so they make great beginner fish!

If you are considering adding this fish to your tank, here are some tips on how to care for balloon belly molly fish at home.

What is the balloon belly molly fish?

balloon belly molly

A balloon belly molly fish, Poecilia sphenops, or the balloon molly fish, is a species of live-bearing fish that originated in Mexico and Central America. Balloon mollies are a fairly new species of freshwater fish, first documented in 1939.

The name balloon belly molly comes from their unique appearance, a rounded body with a long fin on their back that makes them look like they have a small balloon stuffed into their stomachs. They are a peaceful and hardy species of freshwater aquarium fish that reaches around five inches in length.

Balloon belly mollies have an elongated body shape with an underdeveloped lower jaw, which gives them their common name. They come from their tendency to store fat in their abdomen, making it inflate like a balloon. Balloon mollies have been selectively bred into several color varieties over time.

The most common variety is green with red fins, but they can also be found in black, orange, blue, or white varieties as well as several other mixed colors.

Species profile

The balloon belly molly fish belong to the family Poeciliidae, which is a group of live-bearing freshwater fishes. There are over 70 species of Poecilia, with three being popular aquarium fish: balloon belly mollies (Poecilia sphenops), guppies (Poecilia reticulata), and swordtails (Xiphophorus helleri). Balloon belly mollies are native to Texas, Mexico, and Central America.

Datnioides pulcher (Siamese Tiger Fish)

They have been introduced into other areas where they have become invasive. They are omnivores that will eat both plant and animal matter. In their natural habitat, they feed on algae, diatoms, insect larvae, and crustaceans. In an aquarium environment, it’s important to provide them with a balanced diet that includes both plant and animal matter.

Scientific name

The scientific name of the balloon molly fish is Poecilia sphenops


Balloon belly molly fish, also known as poecilia sphenops, are tropical fish that do best in an aquarium with at least a 25-gallon capacity. Mollies come from large rivers and prefer water temperatures in a tropical range of 75 to 79 degrees Fahrenheit. They need lots of oxygen, so make sure your tank is well-oxygenated, and you might want to add some artificial plants or a small waterfall.

That said, Mollies live in various habitats, including brackish water and environments containing hydrogen sulfide in high concentrations. Mollies inhabit an environment where the substrate is largely sandy, with rocks and debris scattered over the surface.

Balloon belly molly size

balloon belly molly

They can grow up to 3 inches (8 cm) in length.

Balloon belly molly tank size

The minimum recommended tank size for the balloon molly fish is 25 gallons (95 liters).

Tank requirements

Balloon mollies are live-bearers, which means they have different care needs than other types of fish. They need a big enough tank with lots of hiding places since they’re shy and easily frightened. As they don’t do well in polluted water, it’s essential to keep them away from power plants or any other water pollution sources, such as factory runoff.

Balloon mollies also prefer cooler temperatures (around 68 degrees Fahrenheit), so be sure your tank has an aquarium heater if necessary. And because balloon mollies are tropical fish, you’ll want to keep their tank out of direct sunlight.

Dalmatian Lyretail Molly (Poecilia latipinna)

It’s important to remember that balloon mollies need regular water changes—about 25 percent weekly—and plenty of oxygen. Because they can grow up to six inches long, it’s best to start off with a 25-gallon tank or larger. Be sure there is enough room for them to swim freely without knocking into each other. A tight lid is important too as they can jump out of tanks!

If you can provide these conditions, you should have no trouble keeping balloon molly fish happy and healthy!

Balloon belly molly tank mates

Although balloon belly molly fish are generally peaceful fish, you should try to keep them in a species-only tank. They may bully other small fish and nip at their fins. It’s also not advisable to house them with large or aggressive fish, as they may become targets. In addition, they prefer a tank with plants so they can hide among them if needed. When choosing tank mates, take their care into consideration—after all, you want your new pets to live long and healthy lives.

Some good tank mates are zebra danios, Rosy barbs, white cloud minnows, Cherry barbs, Zebra loaches, Corydoras catfish, Dwarf Gourami, or angelfish. You can also keep balloon belly mollies with other species of mollies.


balloon belly molly

It is easy to breed balloon mollies. Their population is quite difficult to keep under control.

Most likely, you will see balloon belly molly babies swimming around if you keep females and males together for a short time.

Balloon belly molly pregnant as a livebearer. Therefore, they have the ability to give birth to 20-50 live babies at a time. Balloon belly molly babies are tiny, about 3-4 mm in length, but can swim and eat immediately after they are born.

Despite being so tiny, balloon belly molly babies can be eaten by their parents. You should have plenty of live plants in your aquarium if you plan to breed balloon mollies; baby mollies can hide among these plants, or you can separate pregnant balloon mollies from the tank.

Golden Wonder Killifish (Aplocheilus lineatus)

Are they aggressive or peaceful?

The balloon belly molly is generally a peaceful fish. However, it is suggested that you introduce your new molly into an established tank with other non-aggressive fish. It’s always better to be safe than sorry when introducing new pets. If you’re looking for some great tank mates for your balloon belly molly, consider other calm fish such as shrimp and snails.

Balloon belly molly care

balloon belly molly

It is important to keep mollies’ water clean. Even though they are labyrinth fish, meaning they have an organ that allows them to breathe air directly from the surface of their tank, they still need a well-filtered environment. As long as you do not overstock your tank, your mollies should be fine with regular partial water changes and weekly or biweekly 50 percent full water changes.

Make sure you use dechlorinator when changing your water. Also, make sure there is no ammonia in your tank by using test strips before adding new fish. If ammonia levels are high, it could kill off any beneficial bacteria colonies in your filter and cause major problems in maintaining a healthy aquarium.

Balloon molly fish diet

Mollies are omnivores that enjoy eating live plants and algae, but also benefit from a diet rich in protein-rich foods like brine shrimp and bloodworms.

Lots of algae, live or frozen brine shrimp, mosquito larvae, and daphnia. Avoid high-protein foods (i.e., meaty foods like tubifex worms) because they can cause constipation, which is deadly for balloon belly mollies.

To keep your pet healthy, be sure to feed them regularly—but don’t overfeed!

Since balloon belly mollies are very active and feed constantly, any food left in their tank will quickly spoil and could cause a bacterial infection.


The balloon molly fish can live up to 3 to 5 years.

Parasites and diseases

As with many fish, balloon belly molly fish are susceptible to parasites. Two of their most dangerous parasites are anchor worms and flatworms. It’s important that you inspect your tank on a regular basis and remove any signs of disease or pest infestation immediately.

Datnioides microlepis (The Indo Datnoid)

Keep an eye out for unusual behaviors like scratching, flashing (when a fish rapidly opens and closes its mouth), swimming upside down, clamped fins, loss of appetite, or cloudy eyes; these are all signs of an infection. You should also make sure to quarantine new fish before adding them to your main tank. This will prevent diseases from spreading throughout your aquarium.


One of balloon belly molly fish’s biggest threats is often other fish. In a home aquarium, it may not be a big deal if you lose one or two fish here and there, but in ponds or lakes, predatory fish can wipe out entire populations of mollies in short order. If you see them circling your molly school at feeding time, scoop them up before they get any ideas about making your pets lunch.

Some common predators are bluegill, bass, catfish, crappie, and other sunfish; largemouth and smallmouth bass; walleye; northern pike; perch (including yellow perch); bullheads (including channel catfish); trout; bluegill and pumpkinseed sunfish. In addition, mollies have been seen eating their own young in captivity.

Do balloon belly molly fish make good pets?

Yes, balloon belly molly fish make great pets, and they’re easy to care for. In order to thrive in captivity, these fish require large amounts of oxygen, which means you need a large tank with plenty of water and filtration. They also prefer warmer temperatures than other types of tropical fish, so it’s important to keep your tank at 80 degrees or higher.