Today it’s about the Mollys. The Molly is also known as a short-finned molly and is a real enrichment for every community aquarium with peaceful fish. The fish is also suitable for beginners due to its robustness.

If you choose the Molly, you need not worry if you keep it well and you will have a long-lived aquarium inhabitant. The name Spitzmaulkärpfling comes from the Greek Poecilia sphenops, where sphenops means “pointed head”. The molly belongs to the viviparous toothcarps. The fish actually comes from South and Central America. In the fact sheet and the following guide you will learn more about this beautiful fish.

Molly’s profile

Scientific name: Poecilia sphenops
Known breeding forms: Black Mollys, Gold Powder Mollys, Silver Mollys, Dalmatian Mollys
Origin: Central and South America (fresh and brackish water and slow-flowing waters)
Dissemination: southern Texas over Colombia until Venezuela
Age: 5 years old
Size: 6-12 cm
pH value: 6-8
Water: no special requirements (not too acidic or too alkaline), but sensitive to temperature fluctuations
Water hardness: 10 – 30° dGH
Temperature: 24 – 30° C
Behavior: peaceful
Posture: Company, group (min. 5 animals), in pairs, harem
Nutrition: vegetable food, salad, spinach, algae, live food, frozen food
Diseases: Weakness disease, spot disease
Aquarium size: medium, from 80 cm (100 litres)
Facility: fast growing and lush planting, also floating plants (e.g. waterfriend, hornwort), many hiding places
Ground: undemanding – sand, gravel, stones
Swimming zone: mainly on the top, but with food it also reaches the bottom
Family: Poecillidae
Subfamily: Live-bearing tooth carps (Poeciliinae)
Genus: Broad fin carpelled seedlings (Poecilia)
Order: Dental carbuncles (Cyprinodontiformes)
Subordination: Cyprinodontoidei
Activity: tag active
Reproduction: Livebearers
Breeding: easy
Price: 3-7 USD

Molly’s origin and way of life

Mollys originally come from Central and South America. There they inhabit both fresh water and salty brackish water (salinity of brackish water: 0.1% to 1%). They prefer particularly slow-flowing waters. They are very common along the Atlantic coast. They can be found from Mexico via New Orleans and Florida to North Carolina. Further down on the map it occurs from Venezuela to Colombia.

As an aquarium inhabitant it came in 1999 for the first time to us in Germany, it was known since 1906. Because the Molly loves warm water and it was exposed several times, one can find it as a neozoon also in our nature. Where the water is heated by a power station, for example, it has good chances of survival. In some tropical countries the Mollys have been exposed to fight mosquito plagues.

Appearance and physique

Black Mollys
Black Mollys / © kocsiasany78

In nature the Molly has a grey-green appearance, in the trade you can find many colours. The Black Molly is probably the best known representative of the Mollys, it is also called Wild Molly. The head shape is pointed, the body is very strong in mass.

As members of the livebearers the male also has a mating organ, which was converted from an anal fin. Very large specimens can grow up to 12 cm long. Typical are 6-10 cm.

In Mollys the difference in size between males and females is not as clear as in other fish. The pectoral and ventral fins are usually transparent. Fin formula: Dorsal 8 – 9 (freshwater population), 9 – 11 in (brackish water population) (region: Panama Canal); anal 8-10; pectoral 14; ventral 6. In the middle longitudinal row the molly bears 25 to 30 small scales on its body.

Molly posture

If you want to keep Mollys in the tank, you should consider that they not only need a group and a sufficiently large tank, but also reproduce quickly and easily. As Mollys are quite undemanding towards water and soil, one should, apart from the ideal values, also pay attention that the aquarium water is not subject to strong temperature fluctuations. A minimum temperature of 23° C helps the Molly to feel comfortable. If you set the temperature too low, you risk that your fish are particularly susceptible to disease. If you set the heating too high, you will find few active fish. A heating mat or a heating rod is recommended. By the way, you can observe temperature fluctuations partly by their behaviour, if they feel unwell, they will make a lateral rocking movement.

If you are nice to your Mollys and take good care of them, you will enjoy them for up to 3-5 years. In the natural habitat of the Mollys a male often lives together with several females. You should give the male Molly at least two female partners. If you want more males, you should have a sufficiently large tank, because the black marmoset forms a territory and also defends it. This means stress for the other fish. Molly not only love strong vegetation, but as very active fish they also need enough space to swim.


You don’t have to economize on planting with Mollys. They like large primeval forests full of plants and also very much like Dutch basins. However, there must be enough space for straight long swimming lanes. By hiding places not only the adults can find protection, but also the young fish of the Mollys can survive. Beautiful plants for Mollys are for example the hornwort, because it provides a lot of oxygen, and the Hygrophila.


Also the food is relatively easy with the Mollys. They are very frugal and feed on vegetable food, salad, spinach, algae, live food and also frozen food. If algae are present, they eat plenty of them. The Mollys mainly take their food at the water surface, so a not too fast sinking flake food with high vegetable content is a good choice for the Mollys.

If there is no more food to be found at the surface, the molly will go down to the bottom. Especially when feeding with live food, which sinks to the ground quickly, such as red mosquito larvae. As live food Artemia and mosquito larvae (black, white, red) are suitable. Other aquarium owners are more experimental: small crabs and shrimps, egg yolk (cooked), peas, cucumbers, aphids. I additionally feed with green food tablets.

Behaviour and socialization

The Mollys are very peaceful, full of curiosity and learn quickly. They are constantly on the move and swim big lanes. Towards other peaceful aquarium inhabitants they behave perfectly, you can bring them together and socialize without hesitation. You should be careful in an aquarium that is too small with several Molly males.

Molly species and colours

It is not an easy task to taxonomically assess the black rhinoceros. Diverse, partly highly differentiated populations have been described as separate species. All new names of the species were subsequently made synonymous. The two species P. maylandi and P. mexicana are probably withdrawn and end up as synonyms.

It gets exciting when it comes to the colours. Wondrous creations were created here by breeding and hybrids. Usually the name of the Mollys is based on their appearance. Popular are:

  • Black molly
  • Gold Powder Molly (Goldmolly)
  • Silver Molly
  • Dalmatian Molly
  • Silver Marble Molly
  • Black molly
  • Diamond Molly
  • Gold-Black-Molly
  • Jam Cat Molly
  • Copper Molly
  • Red Leopard Molly
  • Red Molly
  • Saffron White Belly Molly
]In addition, the molly can be distinguished by the tail fin. They are available as fork tail or in the form of lyre. All breeding forms have a shorter life expectancy than the wild form.

Mollys - Differentiate males and females

It is very easy to distinguish males and females in the Mollys. You can recognize it by the anal fin, which has the shape of a rod in the male and a fan shape in the female. On the following picture you can see the difference very well.


Breeding and reproduction of the Mollys is relatively easy. Even without taking special precautions, many specimens will survive if there is enough planting. Mollys like to reproduce a lot.

Molly pregnant

Once the molly is pregnant (difficult to notice in dark specimens), the time until the birth of the little baby fishes usually runs smoothly. The gestation period lasts 26 to 35 days.

Molly birth

At birth 26 to 80 little Mollys are born. At birth they are only 5 to 8 mm tall. The parents usually eat only a few specimens of the newborns. In this video you can watch a Molly birth live:


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Molly Diseases

Also the Molly is not spared from one or the other disease. In some cases the addition of salt is supposed to help, which I haven't tried yet and therefore can only make guesses about the effect. Especially known is the spot disease, which is a parasitosis in freshwater aquariums. Here you can find many white spots on the fish. Admittedly: the diagnosis is quite difficult with a Dalmatian Molly, but with a Black Molly it is easy to recognize. One solution may be to increase the water temperature by a few degrees (to about 26° C). If the disease is advanced, then you need special medication, which probably means a visit to the vet. If the Black Molly gets sick, one should also check the cause. Often it can happen that the pH-values were not kept or the water hardness is not right.

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