Mollies Fish – Black and speckled Yellow Colored Fish

The Mollies fish is a genus of fish of the Actinopterygii class belonging to the family Poeciliidae.

These fish are very common in aquariums around the world due to their ease of conservation and general care.

This genus belongs to a large number of species that have different characteristics.

Characteristics of Mollies Fish: 

The males of this species tend to be smaller, but more elongated and their fins have a greater increase than in females.

The male has a maximum length of six centimeters, while the female measures 10 centimeters. These characteristics make a marked sexual dimorphism in the species of this mollies fish.

They have an algae body, with a slightly pointed head and mouth, where we find very sharp teeth.

mollies fish

Their fins have soft radii. The coloration of the Mollies fish is very diverse, the fruit of the different crosses made by the aquarists.

In a natural state, this fish is black and speckled in yellow, however, for sale we find Mollies black, orange, marbled, white, red, gold, Dalmatian, albino.

The quantity is wide and from time to time, we are surprised by a new Mollies fish hybrid. To distinguish them from the Guppy, the Mollies have a thicker body and their fins are not elongated, rather rounded.

In Mollies fish, sex can be differentiated after 2 or 3 months of life. The females have a body more rounded than the males, more stylized, thin and elongated.

Mollies males have more striking and justify colors than females.

Types of Mollies: 

When we talk about Mollies fish we are generalizing, and including from the denomination “Mollies fish” a good variety of Poecilia.

Some of the best known and that we can find in aquariums around the world are:

Mollies fish ball: 

The Mollie’s ball has the same characteristics as the rest of the Mollies but is more rounded and with a prominent belly.

The colorations of these fish are similar to the rest of the Mollies.

Mollies swordfish or Mollies swordtail: 

This is a fish of which there are many varieties to choose from, in addition, all equally striking for their colors and veils.

It is not usual, but sometimes this fish changes sex, transforming a female into a male.

Mollies Dalmatian fish: 

This is a very striking Mollies, full of black polka dots on a silver background, which has earned him the nickname of “Dalmatian” for the breed of dogs.

It is a variety of Poecilia that comes from Mexico, this species is quiet while active.

Ideally,  should have one male for every 4 females.

Black Mollies: 

The Black Mollies or Mollies with short fins is the most original because of its coloration, completely black in the male.

It is a very calm fish, which can coexist with other Poecilia, even with the risk of hybridizing, since they reproduce easily.


The mollies fish is omnivorous, its food is varied, it can eat live food, dried some scales among others.

This species is necessary plant-based food, the offspring also known as fry are fed with water fleas, crushed flakes, etc.

In the wild, it feeds on worms, crustaceans, insects, algae, and plants. In the aquarium, they will take prepared dry foods willingly.

But from time to time, this breed needs a good supply of algae or spinach, to which we must add brine shrimp, mosquito larvae. It is recommended to feed them two or three times a day but in small quantities.


This fish is peaceful yet adult males can become territorial with other fish in the aquarium.

It is necessary that these fish coexist in groups of one male for every three or five females since it can stun her.

In nature, each male is surrounded by several females. Some good aquarium companions could be some rainbow fish and tetras, which are tolerant to hard water.

It is common for this fish to clean algae in the aquarium, they can coexist well in community aquariums with other species of equal size.


This breed can live well at a temperature between 19 ° to 30 ° C, ideally between 22 ° and 28 ° C.

The water should be a little hard with a PH between 7.0 and 7.5, its size makes it suitable for aquariums of different dimensions.

These can be small, medium or large but the fish must have enough space to move freely.

This must have a good amount of plants so that the female can take refuge when she is going to give birth also so that the fry hide.

For the species to live longer and its life to be healthy it is necessary that the water has a little salt. The salt kitchen should not be used because it has iodine that causes problems to the fish.

This species can live in brackish water even in saltwater.

Distribution and habitat: 

In the wild, it can be found in many parts of the world. Although they are native to the southeastern United States, Venezuela, and Colombia to Mexico.

It is known of isolated populations in some Caribbean islands. They are fish that usually live in the mouths of the rivers.

The reason why they hold a certain degree of salinity in the water. It is not usual that we buy a Mollies raise in freedom, those that we will find in the pet stores, are fish bred in China or in Eastern Europe, only to be commercialized. You may also like to read Neon Tetra


If the justify conditions are met, Mollies’ reproduction is very simple. The gestation of Mollies pregnant fish lasts about 8 weeks. At the end of which we can find more than 100 small fries.

About four weeks before the arrival of the new baby fish, when we are clear that the female is breeding, we have to put it in a separate aquarium, so that it is not bothered by the male and watch the delivery.

At the moment the female has given birth, we will remove it from the pond and return it to the aquarium. It is left to the fry alone, to prevent the female from eating them. You may also like to read Angelfish


The viviparous are fish prone to attack by fungi, white spot and other diseases associated with parasites.

However, the most common in the Mollies is the so-called “Mollies’s disease”. Caused by the bacterium Columnaris, Flavobactetium columnare, which causes deformation in the fish column.

It can be detected that the fish have been attacked, when we observe a change in the skin.

With small white spots, other symptoms are trembling or stop moving, stay lethargic. There are treatments based on potassium permanganate and Terramycin.

In any case, we must isolate the affected fish and consult our fish store.


The Mollies fish are known worldwide for the aquarium, especially because they reproduce very easily. In the wild, they are silvery fish, lightly dotted with black specks.

However, we can find a variety of Mollies fish with different colors, gold, green, even the most demanded, Mollie’s black.

Many of these specimens are the result of the crossing of Poecilia sphenops and Poecilia latrines.

Which are easy to cross, even if we have them in our aquarium. If we do not want them to cross, it is best to keep only one of these species in the aquarium.

We must remember, that they are fish that are better in slightly brackish waters. If the water is sweet and does not have the proper conditions of hardness and alkalinity, it will be exposed to a greater number of diseases.

As a reference: Wikipedia 


Fredric L Triplett

I'm a friendly, hardworking independent farmer. As a high-tech farmer, I'm always looking for ways to improve the quality of my life. I have two girls and one lovely wife who all love me very much. We enjoy spending time together outdoors - gardening, fishing, hunting, etc. Also like to play football and table tennis with friends on the weekends.

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