Facts About Molly Fish

What is Molly Fish?

Molly fish belong to the genus Poecilia, which includes around 30 different fish species. They are native to Central and South America’s fresh and brackish water habitats. Furthermore, Molly fish can be found in both brackish and freshwater environments.

The black Molly (Poecilia Sphenops) is the most common species of molly fish kept as a pet. However, there are many more lovely variations available, including:

  • Sailfin molly (Poecilia Latipinna)
  • Dalmatian molly (Poecilia Dalmatia)
  • Golden comet molly (Poecilia Variegata)

They are well-known for their vibrant colors and playful personality. Therefore, Molly fish are a common variety of freshwater fish in home aquariums.

Furthermore, Molly fish are low-maintenance and make an excellent addition to any fish tank. Molly fish thrive in aquariums with at least 10 gallons of water and should be kept alongside other small, peaceful fish.

They are calm fish who get along well with other tankmates and are not known to be fin nippers. Many do not know that Molly fish are gregarious species that thrive in groups.

A molly fish group should have at least six individuals, but the more, the merrier. Because molly fish are not aggressive toward other fish, they can be kept with a wide range of tank mates.

Molly fish are omnivores, meaning they eat both plants and animals. In the wild, they eat algae, tiny insects, and crustaceans. Molly fish in captivity can be fed a number of commercially available foods.

Types of Molly Fish

Molly fish come in many different varieties, each with its unique coloration and patterning.

Sailfin molly (Poecilia latipinna)

sailfin molly poecilia latipinna

The sailfin molly is the most common variety of molly fish (Poecilia latipinna). The broad, flowing fins and iridescent scales of sailfin mollies distinguish them from others. They are quite hardy, making them perfect for novices.

They are one of the largest molly fish species, reaching 4 inches in length. Sailfin mollies have black fins that are slightly darker than those of other black molly fish.

Black Molly (Poecilia sphenops)

black molly poecilia sphenops

Another popular molly fish is the black molly (Poecilia sphenops). Black mollies are little, only reaching a length of about 2 inches. They are black in appearance with a few white spots on their fins, as their name suggests.

They thrive in temperatures ranging from 68 to 82 degrees. Black mollies are shy fish that thrive in tanks with plenty of hiding spots, preferably at least 30 gallons.

Dalmatian molly (Poecilia dalmatina)

dalmatian molly poecilia dalmatina

The Dalmatian molly is a beautiful variety of molly fish that is covered in large, dark spots. Dalmatian mollies grow to be about 3 inches in length and are a dark silver color with black spots.

Balloon molly (Poecilia mexicana)

balloon molly poecilia mexicana

The balloon molly is one of the most unique-looking types of molly fish. As their name suggests, balloon mollies are round and bloated in appearance.

Balloon mollies are born without scales, but they develop them as they mature. They come in a variety of colors, including black, silver, gold, and even stripes.

Lyretail molly (Poecilia sphenops)

lyretail molly poecilia sphenops

Lyretail mollies are distinguished by their forked tails and long, flowing fins. They are comparable to sailfin mollies in size, reaching up to 4 inches in length. Lyretail mollies are available in a variety of colors, including black, silver, gold, and fluorescent green.

Molly fish is a common freshwater aquarium fish. They are distinguished for their brilliant colors and energetic dispositions. Molly fish come in a variety of colors and patterns, each with its own personality.

Molly Fish’s Appearance

facts about molly fish

Molly fish come in a variety of colors, including black, white, silver, gold, and even blue. Some molly fish have stripes or spots on their bodies, while others may be solid-colored. The color of a molly fish can help to camouflage it from predators in the wild.

Molly fish are typically 2-4 inches in length, although some larger varieties can grow up to 6 inches long.

Molly fish typically has an oval-shaped body with a blunt head. The fins of a molly fish are often transparent or translucent. The caudal fin (tail fin) of a molly fish may be forked or rounded in shape.

Molly Fish’s behavior

Molly fish are social creatures that live in groups. They prefer to be with other molly fish, but can also get along with other peaceful fish. Molly fish are not aggressive and will not bother other fish unless they feel threatened.

Molly fish are active during the daytime and like to swim around a lot. They are known for their playful nature and will often chase each other around. Molly fish are also good jumpers, so it is important to have a tight-fitting lid on your aquarium.

Furthermore, they are generally peaceful, but they can become aggressive if they feel threatened. If you keep molly fish with other types of fish, make sure to provide plenty of hiding places and swimming space. Otherwise, the mollies may chase and nip at the other fish.

Male vs. Female Molly Fish

male vs female molly fish

When considering purchasing Molly Fish, it is important to know the difference between male and female fish. While both sexes are equally beautiful, they do have some different characteristics.


Size is the most obvious difference between the sexes in molly fish. Females are typically much larger than males, growing up to four inches long compared to the two-inch maximum length of males.

Females also have a more rounded body shape, while males tend to be thinner and sleeker.


Another easy way to tell male and female mollies apart is by looking at their fins. Females typically have shorter, less showy fins than males.

For example, the fins of a female black molly fish are much shorter than those of a male black molly fish. The male fins are also more pointed.


Males and females also tend to differ in coloration. Males are often more brightly colored than females, with richer colors and more intense patterns.

In some cases, the difference in color between the sexes can be quite striking. For example, male guppy fish are usually brightly colored, while female guppies are mostly gray or brown.


Males and females also tend to exhibit different behaviors. Males are often more active and aggressive than females, and they are also more likely to display courtship behaviors such as chasing and nipping. Females, on the other hand, tend to be more passive and less interested in mating.


When it comes to breeding, males and females have different roles. The male will chase the female and attempt to spawn with her. If the female is not ready to breed, she will usually swim away from the male.

If she is ready to breed, she will allow him to catch up to her and spawn with her. After spawning, the female will often eat the eggs that are produced.

Which fish do Molly Fish get along with?

Molly fish are peaceful by nature and do best with other peaceful fish that are of a similar size. Good choices for tank mates include other live-bearing fish such as guppies and platies, as well as peaceful corydoras catfish. You can choose the following fish as its tank mate:

  • Guppies
  • Platies
  • Swordtails
  • Corydoras catfish
  • Harlequin Rasboras

However, avoid keeping Molly Fish with larger, more aggressive fish as they may become bullied or stressed. Molly Fish does not do well with large, aggressive fish such as Cichlids or Oscar

Fish. They also do not do well with fish that are known to nip at the fins of other fish, such as Tetras.

It’s also important to provide plenty of hiding places and plants in the aquarium for your Molly Fish to feel secure.

When choosing tank mates for molly fish, it is also important to consider their water requirements. Molly fish prefer water that is soft to medium in hardness and slightly alkaline, so it is best to avoid fish that prefer hard or salty water.

Overall, the best thing to do is to research the specific needs of any potential tank mates before adding them to your aquarium.

How long Does Molly Fish live?

Molly fish are live-bearing freshwater fish that belong to the Poeciliidae family. The average lifespan of a molly fish is 2 to 5 years, but some may live up to 10 years with proper care.

Molly fish are hardy and adaptable, but they are also sensitive to changes in water conditions. Regular water changes and close attention to water quality will help keep your molly fish healthy and extend their lifespan.

How long can a Molly Fish live without food

Molly fish are a type of freshwater fish that can live for a relatively long time without food. Molly fish have been known to survive for up to six weeks without food! This is because Molly fish can store large amounts of fat in their bodies, which they can use as energy when there is no food available.

However, it is important to note that Molly fish will eventually die if they do not have access to food for an extended period.

Without food, molly fish can only survive for so long before they start to experience organ failure and other serious health problems. It is therefore important to make sure that your molly fish have a reliable source of food and that they are getting enough to eat regularly.

How do Molly Fish sleep

how do molly fish sleep

Molly fish typically sleep during the night, but they can also take short naps during the day. Molly fish typically sleep for short periods throughout the day and night. They are not true sleeper fish like some other species of fish.

However, they will often take brief naps during the day when they are not active. When they sleep, their body slows down, and they become less active. Their eyes may also close or become cloudy.

Molly fish usually sleep on the bottom of the tank or near plants and other objects in the aquarium. They will often lie on their side or curl up into a ball when sleeping. Molly fish may also rest on top of rocks or other decorations in the tank.

In the wild, molly fish live in ponds and rivers that have a natural day/night cycle. The water temperature and light levels will change throughout the day, signaling to the fish when it is time to sleep.

How to care for their sleep? Well, the best way to provide your molly fish with a proper sleep schedule is to mimic their natural environment as closely as possible.

  • It is important to provide molly fish with plenty of hiding places in the aquarium, so they feel safe and secure. This will help them to relax and sleep peacefully.
  • Provide your molly fish with plenty of plant cover and hiding places such as caves, tunnels, and Driftwood. You should also avoid disturbing your molly fish while they are sleeping.
  • In your home aquarium, you can recreate this natural cycle by turning off all lights and raising the water temperature at night. This will help your molly fish relax and fall asleep.
  • It is important to make sure that your aquarium is well-ventilated so that your fish do not overheat during the night.

How to choose a Molly Fish

how to choose a molly fish

Choosing the right Molly Fish for your aquarium can be a difficult task. There are so many different kinds of Molly Fish available, and it can be hard to know which one is the best for your specific setup. Here are some things to consider when choosing a Molly Fish:


First, consider the size of your aquarium, as 30-gallon is a good start.

How big do you want your fish to be? Some Molly Fish can grow quite large, while others stay fairly small, so you need to make sure that your aquarium can accommodate a full-grown Molly Fish. If you have other fish in your aquarium, you need to make sure that they will not be bullied or outcompeted for food by a Molly Fish.


Do you have a specific color in mind for your Molly Fish? Again, there is a wide variety of colors available, so take some time to browse and see which one catches your eye.


Some Molly Fish are known for being nippy and aggressive, while others are much more laid back. It’s important to consider the other fish in your aquarium and choose a Molly Fish that will get along well with its new tank mates.


Another thing to consider when choosing a Molly Fish is the health of the fish. Make sure to buy a Molly Fish from a reputable dealer who can provide you with a health guarantee. You also want to make sure that the fish has been raised in good condition. A healthy Molly Fish will have bright colors and clear eyes.

How much does Molly Fish cost?

molly fishs appearance

Molly fish are not particularly expensive fish, and they can typically be purchased for around $5-$10 each; some molly fish can cost up to $20, depending on the breeder and demand.

However, the exact price will vary depending on the specific type of molly fish and where it is being purchased from. Pet stores will typically charge more for molly fish than online retailers or specialty aquarium stores.

Some specialty stores may charge more for certain types of mollies, so be sure to check around before making your purchase.

How many Molly Fish in a tank

molly fishs behavior

The answer to this question depends on many factors, such as the size of your tank and the type of Molly fish you have. Mollies are also relatively active fish, so they need plenty of space to swim around.

A good rule of thumb is to have at least 10 gallons of space for every two adult Molly fish. So, if you have a 20-gallon tank, you could theoretically keep four adult Molly fish in it. However, it is always better to err on the side of caution and provide more space rather than less.

Can Molly Fish live without a filter

One of the most important things to do for Molly Fish is to maintain a clean and filtered tank. This is because Molly Fish are very sensitive to water conditions and can easily get sick if the water is not clean.

So, can Molly Fish live without a filter? The answer is yes, but it is not recommended. Without a filter, the water in the tank will need to be changed more frequently and there is a greater risk of the fish getting sick.

If you decide not to use a filter, there are some things you can do to help keep your Molly Fish healthy.

First, you will need to do a more frequent water change. At least once a week, you should remove all of the water from the tank and replace it with fresh, clean water.

You will also need to be more diligent about cleaning the tank itself, as debris can build up and pollute the water without a filter to trap it.

Can Molly Fish live without a pump

Water pumps help to keep the water in their tank clean and oxygenated? Without a water pump, the water in their tank can quickly become stagnant and harmful to the fish.

While molly fish can technically live without a pump, it is not recommended. A pump helps to keep the water moving and provides the necessary aeration for molly fish. Without a pump, the water in an aquarium can become stagnant and dirty, which can lead to health problems for molly fish.

If you decide not to use a pump in your aquarium, it is important to take extra care to clean the tank regularly and provide plenty of aeration. An air stone can help to keep the water oxygenated.

Molly fish are hardy creatures, but they still need proper care to thrive. Without a pump, an aquarium can be more difficult to maintain.

Can Molly Fish live without a heater

Molly fish are tropical species of fish that require warm water to survive? In the wild, they typically inhabit waters with temperatures between 77 and 86 degrees Fahrenheit.

As such, they are not well-suited to living in cooler temperatures and will struggle to survive in water that is below 70 degrees Fahrenheit.

While molly fish can technically live without a heater, it is not recommended as they will not thrive in cooler conditions.

If you must keep molly fish without a heater, it is important to maintain a consistent water temperature and provide plenty of hiding places for them to retreat to when necessary.


Molly fish is a great option for beginner aquarium enthusiasts. They are relatively easy to care for and can brighten up any tank with their vibrant colors. Although they are not the longest-lived fish, with proper care, mollies can thrive in captivity for several years.

Molly fish are also known to be good parents, often taking care of their young until they are old enough to fend for themselves. For those looking to add a little excitement to their aquarium, molly fish is definitely worth considering! Thanks for reading!

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Kevin Mills, the founder of Nationalparkaquarium.org


-- Founder --

I'm Kevin Mills, the founder of Nationalparkaquarium.org, where I share my deep passion for aquariums and aquatic life. With over 20 years of experience in fishkeeping, covering everything from tending to saltwater and freshwater tanks.

Kathleen Wood


-- Interrogator --

Kathleen Wood, a seasoned marine biologist, possesses a wealth of knowledge and experience in her field. Her research on tropical fish biodiversity spans over three decades, and she has contributed numerous scientific papers on aquatic life.