Black Molly

The Black Molly is arguably the most universally recognised aquarium livebearer, with its uniformly jet-black body making it one of the few entirely black aquarium fish available to beginners. It has been a fixture of the hobby since the mid-20th century and remains a bestseller in aquarium shops everywhere.

Poecilia sphenops in its black form is hardy, adaptable, and tolerant of a wide range of water conditions including slightly brackish water. Mollies are unique among common livebearers in their preference for harder, more alkaline, and slightly saline water, and they appreciate the occasional addition of aquarium salt.

Black Mollies are prolific breeders and the fry are large enough to be immediately visible and easy to raise. The all-black colouration makes them excellent contrast fish alongside brightly coloured tankmates.

Water: 23–28 °C, pH 7.5–8.5, hard and slightly saline (1–2 g/L salt beneficial); poor in soft acidic water. Tank: 80 L minimum; plants for cover; good filtration as mollies are messy feeders. Feeding: Omnivore with strong herbivore tendency; algae-based flake essential; supplement with vegetables. Breeding: Very prolific; females drop 20–100 fry every 4–8 weeks; fry are large and robust. Compatibility: Generally peaceful; avoid very soft-water species; males may harass females.