Max Size: 12cm

Mollies (Poecilia Sphenops)

Mollies are colourful live-bearing freshwater fish. There are currently 39 known species in this genus. Mollies are one of the most commonly kept fish amongst hobbyists and are perfect for beginner aquarists as they are very hardy and easy to take care of.

Mollies are active and sociable and enjoy schooling together. However, a shoal should be predominantly female because males are known for harassing and stressing out females, and you should have at least four or more individuals.

You will see plenty of unique personalities and exciting behaviours begin to develop. For example, Mollies are peaceful fish most of the time but can show signs of aggression when surrounded by aggressive tank mates or are overcrowded. Therefore, it’s essential that their tank is big enough and that they have suitable tank mates.

Suitable tankmates can include Corydoras Catfish, Danios, Dwarf Gouramis, Cherry Barbs, Rasboras, Rosy Barbs, Platies, Tetras and Loaches. Most invertebrates such as Shrimp and Snails will be fine living alongside your Mollies also as they will mostly ignore them. However, it is recommended that you avoid larger, more aggressive fish such as Cichlids as these will try to eat your Mollies and may attack and stress them out to the point of death.

There are plenty of different varieties of Mollies, although most are very similar to the common Molly. The main differences are patterns and colours, but shapes and sizes can differ too.

The common Molly has a flattened body, is tall in the middle and narrows towards a point at the mouth. Their caudal fin is a large fan shape that can be colourful or transparent, and their dorsal fin can be elevated as a fan, resembling the caudal fin or flattened against the body.

You also have the Black Molly Fish that is black all over, as well as the Sailfin Molly. The Sailfin Molly variety is bred in several colours and patterns, and their most distinctive feature is their large dorsal fin which is much taller and runs from behind the head to the caudal fin.

Lyretail Mollies stand out because of their caudal fin; the top and bottom of the fin narrow into a point that trails behind the rest of the fish. Other popular Mollies include the Balloon Molly, Dalmatian, Molly, Red Molly, the Orange Molly and the White Molly.


Lyretail Molly
Dalmatian Molly
Lyretail Molly
Balloon Molly
Sailfin Molly
Dalmatian Molly
Quick Facts
Scientific NamePoecilia Sphenops
Other NamesShort-finned Molly, Sailfin Molly, Common Molly, Black Molly, White Molly, Golden Molly, Lyretail Molly, Dalmatian Molly
OriginsColombia, Mexico, Venezuela
Aquarium LevelAll Levels
DifficultyBeginner - Intermediate
Best kept asGroups 5+
Lifespanup to 5 years
Water Parameters
Water TypeFreshwater
PH6.5 - 8.5
GH15 - 30
72 - 78℉
22.2 - 25.6℃


In the home aquarium, the Mollies will readily accept most good quality dried foods such as granules, flakes and sinking pellets. These modern food products have been developed to provide all adequate nutrition to maintain your fish's health and dietary requirements.

Providing additional foodstuffs such as live, frozen, and freeze-dried meals such as bloodworm, daphnia, and tubifex once or twice a week will provide additional benefits to your fish's health and well-being but is not a must for this fish.

It should be noted that bloodworms should only be given as an occasional treat and should not be used as the staple diet as they are difficult for fish to digest and can potentially cause blockages.

This fish is an omnivore in the wild, meaning it will consume some vegetable matter. Although most modern fish foods take this into account and include them in their products, you can still supplement your fish's diet with blanched vegetables such as spinach, broccoli, and zucchini. Ensure you do not overfeed your fish and remove any leftovers the following day.

Sexual Dimorphism

It is relatively straight forward to distinguish male from female Mollies. Males are smaller, brighter coloured and possess a pointed anal fin called the gonopodium. In contrast, females are larger than males, have rounder stomachs, and their anal fin is fan-shaped rather than pointy.

Other Livebearers of interest

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Dusky Millions Fish(Phalloceros caudimaculatus)
Humpbacked Limia(Limia nigrofasciata)
Merry Widow Livebearer(Phallichthys amates)
Platies(Xiphophorus maculatus, Xiphophorus variatus)
Spotted Skiffia Multipunctata(Skiffia Multipunctata)
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Date Added: 07/05/2021 09:31:08 - Updated: 19/01/2022 14:54:50