Sailfin molly

Poecilia latipinna

FreshwaterBrackishFish

Care at a glance

Temperature: 70–79°F (21–26°C)
pH: 7.0–8.0
Adult size: 4.7 in (12 cm)
Minimum tank: 24 gal (90 L)
Temperament: Mostly peaceful
Social behavior: Social
Swim level: Middle
Difficulty: Easy
Breeding: Easy
Rarity: Very common
Origin: Mexico
Family: Poeciliidae

Overview

They are social and do best in a group with more females than males, in a tank of around 90 liters or larger to suit their size. They cruise the middle and upper water and stay mostly peaceful, though males can get pushy with each other. They graze a lot, so include algae and vegetable matter alongside flake and the odd live or frozen treat. Keep the water hard and alkaline, pH about 7 to 8, in the low to mid 20s C.

In the wild

Sailfin mollies come from the coastal lowlands of the southern United States and Mexico, including brackish marshes, ditches, and slow streams. They tolerate a wide salinity range, from fresh to brackish, and like warm, hard, alkaline water with plenty of algae to graze. In the aquarium they appreciate hard water with a higher pH and open swimming room. Some keepers add a little marine salt, though it is not strictly required for the freshwater form.

Good to know

This is a livebearer in the family Poeciliidae, and one of the larger mollies at up to about 12 cm. As the name suggests, mature males develop a tall, sail-like dorsal fin they use in displays. They bear live young rather than laying eggs, and females can produce broods every few weeks. Lifespan is usually two to three years.

Did you know

Males flare that big sail fin in a side-on display to impress females and warn off rival males. The fin is far larger in the sailfin molly than in the common molly, and getting it to develop fully takes good food and space while the male is growing.