Pacific molly

Poecilia butleri

Also known as Butler's molly

FreshwaterFish

Pacific molly (Poecilia butleri) — Finn Wigström · CC BY-SA 4.0

Care at a glance

Temperature: 72–81°F (22–27°C)
pH: 7.0–8.2
Adult size: 2.8 in (7 cm)
Minimum tank: 29 gal (110 L)
Temperament: Peaceful
Social behavior: Social
Swim level: Middle
Difficulty: Medium
Breeding: Easy
Rarity: Rare
Origin: Pacific slope, Mexico to Panama
Family: Poeciliidae

Overview

The Pacific molly is a sturdy shortfin molly for a colony, and because males can be pushy it pays to keep several females for each male. It patrols the middle and upper water and grazes surfaces constantly, so it wants open swimming room and good light. It is generally peaceful and community-safe with other firm, hard-water fish, though it is too big and busy for delicate nano species. Its diet leans heavily vegetarian: give it algae, spirulina flake, blanched greens, and biofilm, rounded out with pellets and frozen foods. A group needs about 110 liters or more.

In the wild

Poecilia butleri ranges down the Pacific slope of Central America, from Mexico southward, in coastal streams, lagoons, and estuaries where algae and plants grow thickly. It likes hard, warm water, pH around 7.0 to 8.2 and 22 to 27 degrees Celsius, with strong light for algae and open current. It tolerates a little salt because it lives where fresh water meets the sea, but salt is not required to keep it well.

Good to know

Poecilia butleri is a shortfin molly in the family Poeciliidae, described by David Starr Jordan in 1889. Males reach about 7 centimeters and females somewhat more, without the tall sail of the sailfin mollies. It is a livebearer that produces large broods, often 20 to 60 young, and breeds readily, though males can be hard on females and some adults eat fry, so cover helps.

Did you know

Most of the mollies that made the group popular in aquariums come from the Atlantic and Gulf side of the Americas. This one is a Pacific-slope species, feeding largely on algae and detritus in coastal waters that face the other ocean.