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Mollies: Complete Care Guide (Diet, Tank & More)

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Mollies are a great fish to add to any community home aquarium. They are peaceful fish that are easy to care for and come in a variety of colors!

Keep reading to learn everything you need to know about mollies and how to care for them! 

Molly Fish Care Guide

Scientific NamePoecilia sphenops
Common NamesMolly fish, Mollies
Size3.5 to 4.5 inches
Minimum Tank Size10 Gallon Tank
Spotted Black Molly Poecilia sphenops

Mollies grow to between 3.5-4.5 inches and are a peaceful addition to any aquarium. They come in a variety of colors such as black, white, spotted, and gold. They are also hardy fish that are great for beginner aquarists.

Appearance & Temperament


Molly fish come in a wide variety of colors and patterns as there are numerous variants to the common molly.

Most mollies have a similar body and shape to the common molly, much like a platyfish. They have more of a flattened body with a triangle-shaped head.

They tend to be wider in their midsection and taper down to the snout and base of their tale. 

Temperament and Behavior

Mollies are very peaceful fish and would do great in a community tank. There are some instances when a molly fish might exhibit aggressive behavior.

However, this is typically only during times when the molly is stressed due to an overcrowded tank or other aggressive tank mates.

They are very sociable and like to move around in groups. If you opt to have more than a small group of mollies it is recommended the shoal should be more females than males to reduce the risk of stress.

Also, it is best to keep mollies in a group of their own kind of four at the very least, larger groups are preferable.

Lifespan and Size

Molly fish are hardy fish, however, they are prone to diseases with poor tank conditions. With the proper care, the molly fish will live for about three to five years on average. Some molly fish species are more prone to disease than others.

Molly fish on average will be about 3.5 to 4.5 inches on average when they are fully grown. Though they are smaller fish they have big personalities. Some species of molly fish can grow up to five or six inches.

Sex Differences

With a common molly, male, and females are fairly easy to distinguish. Typically the males are smaller than the females when they are fully grown.

There will also be differences in their anal fins, the male’s anal fin is pointed while the female’s is broad and fans out.

Also, a lot of female mollies have a vivid “gravid” spot that is actually where they will carry their pregnancies.

Types of Mollies

As previously stated there are many different variants of a molly fish. Typically they are classified into two main groups: shortfin mollies and sailfin mollies.

Shortfin mollies have a body shape similar to a platy. They have a deeper chest and belly with smaller tails and fins.

Sailfin molly

Sailfin mollies have larger dorsal and tail fins. Oftentimes they are larger than shortfin mollies. 

Common types of mollies are:

  • Black Mollies: The black molly is the most common variant of molly fish. Their bodies will be covered in a solid black color.
  • Dalmation Mollies: Another popular molly is the dalmatian molly. They have a white or silver body with black specks all over. They received their name by having the patterns of a dalmatian dog.
  • Balloon Mollies: Balloon mollies are plump and have rounded bellies. This is due to a genetic mutation that curves their spine. This curvature compresses their organs which creates a rounded belly look. This molly species can be found in a few different colors black, white, orange, silver, and yellow.
  • White Molly Fish: Even though these mollies lack as vibrant colors as other variants, they have a striking appearance either way. Their bodies are a silvery color or a milky white.
  • Gold Doubloon Mollies: With a striking appearance this molly variant is another popular choice amongst aquarists. Their bodies are two-toned with the front half being a vibrant yellow. The lower half of their body is pure black.

Diet and Feeding

In the wild the molly fish will feed off of plants, algae, and invertebrates. They are omnivores and need a varied diet to have a well-balanced diet that should be replicated in captivity.

The baseline of their daily diet should be high-quality flakes or pellets.

Even though they are not considered algae eaters they will snack on the algae that is in your tank, helping maintain your water parameters.

This is because the molly fish in the wild will mostly consume plant-based foods.

Because of this, the addition of blanched vegetables such as lettuce, spinach, or zucchini are great options.

To continue with a varied diet, giving mollies snacks that are high in protein is a good idea.

Mollies will eat live frozen foods, live foods are often a better choice as this will provide them stimulation while catching their snack.

Great options for live or frozen foods are brine shrimp, bloodworms, or daphnia.

As with any fish, you will want to avoid overfeeding as well as excess waste in your tank. It is recommended to feed molly fish about two times a day as they do not need to eat often.

Keep in mind to only feed them what they can eat within about two minutes. Always remember to remove excess foods after feeding times to maintain water conditions.

Ideal Tank Mates for Mollies

As mentioned earlier, molly fish are very peaceful and would do well in a community tank. They will get along with a wide variety of similar nature fish leaving you with a wide variety of options.

It is also important when choosing tank mates that they are compatible besides their temperament.

This means you will need to make sure the tank mates need to have similar water parameters and tank conditions of the molly fish. 

Great tank mates for molly fish:

  • Platies
  • Bristlenose Pleco
  • Yoyo Loach
  • Neon Tetras
  • Guppy Fish
  • Swordtail Fish
  • Celestial Pearl Danio
  • Cardinal Tetras
  • Dwarf Gourami
  • Harlequin Rasboras
  • Cory Catfish

This is just to name a few options for tank mates! Molly fish also get along with nonfish tank mates such as shrimp and snails.

Although there is a wide variety of options for tank mates, you should avoid certain fish as tank mates.

Fish that are known to be aggressive should be avoided, as well as fish that are much larger than the molly. This is to prevent stress as well as injury to your molly fish, or even their death.

Tank mates to avoid for molly fish:

  • Oscars
  • Jack Dempesey
  • Tiger Barb
  • Flowerhorn Cichlid

Aquarium Setup & Tank Conditions

As with most fish it is always best to replicate their natural habitat inside the tank.

Although the mollies are hardy and can be very adaptive to their environment there are certain water parameters you will want to follow for molly fish.

In the wild, the molly fish live in warm waters that have a more neutral pH level as well as harder water.

However different species may need slightly different water parameters than the common molly.  General water parameters for molly fish:

  • Water Temperature: 72°F to 80°F
  • pH Levels: 7.5 to 8.5 
  • Water Hardness: 20 to 30 KH

Mollies should be housed in a tank size no less than ten gallons. This will house about three of four mollies depending on size.

However, mollies love to be a part of a larger group, requiring a larger tank size.

For mollies, it is a general rule to have at least three gallons per molly. However, if they are a sailfin molly variation then you will want to start with a 20 or 30-gallon tank as they are larger than the common molly.

Aside from setting up the right water parameters for the tank, it is important to also replicate their natural habitat in the tank environment as well.

When setting up a tank for molly fish you will want to opt for a good filtration system. This is because even though the molly fish are small they create a lot of waste.

The filtration system will need to keep up with the waste to maintain water parameters.

For mollies, there is more of a range of options in the substrate as opposed to most fish. This is because molly fish tend to stay in the middle or upper levels of the water.

This means there is a low risk of the mollies getting hurt from gravel or rock substrates.

However, mollies love having plants in their environment, because of this a sand substrate would be best.

Adding several different live plants to your molly tank is most suitable for them to thrive. Because of this, having plenty of vegetation is important for molly fish.

The molly fish will use these plants for shelter as they like to hide amongst them.

Keep in mind Molly fish are active and need open areas they can swim around as well.

Some great options for live plants in your molly fish are tall plants like anubias nana as well as shorter options like java fern.

This will give the mollies a wide variety like their natural habitat also the plants should be placed along the perimeter of the tank.

Rocks as well as caves are also great additions to the molly tank. Even though they are not bottom dwellers, they like to hide in caves or behind rocks sometimes.

Other decorations that create hiding spots are suitable as well for molly fish.

Mollies do not need special lighting requirements and a standard light is fine as you will need the light to keep the plants healthy.

How to Breed Mollies

Molly fish are quite easy to breed, as breeding often happens without any intervention from  you. They will spawn several times in their lives as they breed often as well.

However, it is best to maintain a controlled environment for the sake of the fry and their survival after birth.

Even though the molly fish do not often need intervention to start breeding there are steps you can take to initiate the process. You will want to choose the molly pair to use in the breeding tank, females tend to prefer the largest male in the tank.

The water in the breeding tank should be clean, and at a temperature of about 78°F. When the breeding tank is ready you can place the pair in the tank.

Typically you will notice the male performing the courting in the tank. If after about two days the female fish shows no interest in the males’ courting, then swap the male out for a different male.

When the female is ready to breed with the male, she will allow the male to fertilize. This is done by the male transferring milt into the female through his anal fin.

The molly fish are livebearers and gestation will take up to 45 days until the female gives birth. Female molly fish can give birth to up to 100 fry at once.

As the female prepares to give birth to the fry she will hide in a dark and secluded spot in the tank.

Molly fish are not paternal and can be removed after the female is done giving birth, as the adult mollies may eat the fry.

Because of this, using a breeding box may be best as it will let the fry get away from the female as she stays in the breeding box.

Origin & Distributions

Molly fish are one of the most popular freshwater species as they come in a wide variety of looks and are easy to care for.

Mollies are found in the wild throughout North and South America. More specifically the molly fish can be found along the Gulf and Atlantic coast.

Mollies are very common in their wild habitat, however, mollies that are wild-caught are typically a dull silver or gray color.

The colorful species of molly that you would typically see in the freshwater trade are those bred in captivity. 

As molly fish bred in captivity are cross-bred to create all the different variants of bright colors and patterns.Today most mollies are bred in Asia and shipped throughout the world.

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