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Maximum size : 12 cm

Mollies - Poecilia Sphenops : Complete Fish Profile & Care Guide

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Mollies (Poecilia Sphenops) are an amazing and diverse group of freshwater livebearers with a range of 39 species in the genus. A popular choice among hobbyists, these fish are perfect for beginners as they are hardy, easy to care for and showcase unique personalities and behaviours. These active and sociable fish are mostly peaceful but can exhibit aggressive behaviour if overcrowded or kept with aggressive tank mates. Thus, it is crucial to provide them with ample space and select suitable tank mates such as Corydoras Catfish, Danios, Dwarf Gouramis, Cherry Barbs, Rasboras, Rosy Barbs, Platies, Tetras and Loaches. Interestingly, Mollies are best kept in a predominantly female shoal as males are known to harass and stress out females. It would be best if you aimed to keep at least four or more individuals together to enjoy their social behaviours and unique personalities. These fish have a flattened body that tapers towards the mouth and have large, colourful or transparent caudal and dorsal fins that vary in shape. There are many different varieties of Mollies, including the black Molly, the Sailfin Molly, the Lyretail Molly, the Balloon Molly, the Dalmatian Molly, the Red Molly, the Orange Molly, and the White Molly. So, whether you choose the striking black Molly or the uniquely shaped Lyretail Molly, you can enjoy these captivating fish's beauty and fascinating behaviours.

Mollies Photos

Sexual Dimorphism

Differentiating between male and female Mollies is a straightforward task. Males are smaller, brightly 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 pointed. These distinctions are easy to spot with a keen eye, making it an exciting endeavour for any aquarist.

Quick Facts

Scientific NamePoecilia Sphenops
Year Described1846
Other NamesShort-finned Molly, Sailfin Molly, Common Molly, Black Molly, White Molly, Golden Molly, Lyretail Molly, Dalmatian Molly
OriginsColombia Venezuela Mexico
Max Size12 cm
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

Natural Habitat

The natural range of Mollies spans from Colombia and Venezuela to Mexico, with separated populations on some Caribbean islands. Although wild fish are scarce in the hobby these days, with the majority of mass-produced sales taking place in Eastern Europe and the Far East, feral or introduced populations also exist in several countries, including the United States, Japan, Singapore, and even Eastern Europe. In the wild, Mollies are typically found in shallow parts of rivers and streams with sandy substrate covered in debris and rocks, often surrounded by aquatic plants. However, these versatile fish can also be found in various habitats, including coastal sea waters and brackish swamps. It's fascinating to consider the adaptability of these creatures and the various environments in which they thrive.


Breeding Mollies is a straightforward process, provided the right water conditions are met. However, these fish reproduce in a standard livebearer style, with males often displaying persistent courtship behaviour towards females. To mitigate this behaviour, it is recommended to maintain a ratio of several females to every male. Creating an aquarium environment with plenty of areas of dense planting is essential. This allows mollies to feel secure, facilitates giving birth, and provides cover for the fry, increasing the survival rate of the young. After a gestation period of around eight weeks, it's not uncommon to have large broods of up to 120 fry. However, adult fish will prey on their young, making it essential to remove the pregnant females to a separate breeding tank where they can give birth safely before returning them to the main aquarium. Using breeding traps or nets is not advised, as their small size makes them unsuitable for raising fry. The fry is relatively large at birth and will immediately accept powdered flake food or baby brine. Raising Mollie fry to maturity requires dedication and attention to detail, but the rewards of watching them grow and thrive are undoubtedly worth the effort.

Diet & feeding

5 / 5 Mollies are known to be omnivorous, with their wild diet consisting of detritus and zoobenthos. In captivity, these fish will readily accept a wide range of foods, including high-quality flake food, as well as live and frozen options. However, it is important to note that a substantial portion of their diet should comprise vegetable matter, such as blanched spinach, zucchini, or vegetable flake. Providing a varied and balanced diet for Mollies is key to maintaining their health and ensuring optimal growth and development.

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