TankBud

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
Livebearer · Easy
Rarity
Rare
Family
Poeciliidae
Origin
Pacific slope, Mexico to Panama

Overview

The Pacific molly is a sturdy shortfin molly that suits a colony in a hard-water community tank. It is best for a keeper with a little experience.

Did you know

Most of the mollies that made the group popular in aquariums come from the Atlantic and Gulf side of the Americas. The Pacific molly feeds largely on algae and detritus in coastal waters that face the other ocean.

Caring for the Pacific molly

Keep Pacific mollies as a colony in a tank of 29 gal (110 L) or larger. They patrol the middle and upper water and graze surfaces constantly, so give them open swimming room. Strong light keeps algae growing for them to graze, and they like some open current.

Give them hard, warm water at 72 to 81°F (22 to 27°C) and a pH of 7.0 to 8.2. They tolerate a little salt, but you do not need to add any to keep them well.

The Pacific molly's diet leans heavily vegetarian. Give it algae, spirulina flake, blanched greens and biofilm, rounded out with pellets and frozen foods.

Pacific mollies are generally peaceful and safe with other firm, hard-water community fish. They are too big and busy for delicate nano species. Males can be pushy and hard on females, so keep several females for each male.

Females grow somewhat larger than males. The Pacific molly is a livebearer that breeds readily and produces large broods, often 20 to 60 young. Some adults eat fry, so give the young plenty of cover.

Good to know

The Pacific molly, Poecilia butleri, is a member of the family Poeciliidae. David Starr Jordan described it in 1889. Unlike the sailfin mollies, neither sex grows a tall sail.

In the wild

The Pacific molly ranges down the Pacific slope of Central America, from Mexico to Panama. It lives where fresh water meets the sea, in coastal streams, lagoons and estuaries thick with algae and plants.

Weekly picks

Tank mates

The Pacific molly is a peaceful, social species that keeps to the middle. These picks share a community profile with it, are safe together in both directions, and overlap on water type, temperature and pH.

Check the full mix in the stocking calculator

Common questions

What size tank does a Pacific molly need?

A Pacific molly needs at least 29 gal (110 L). It spends most of its time in the middle.

What temperature and pH does a Pacific molly need?

A Pacific molly is comfortable at 72–81°F (22–27°C) with a pH of 7.0–8.2.

What does a Pacific molly eat?

A Pacific molly eats a diet that leans heavily vegetarian, with algae, spirulina flake, blanched greens and biofilm. Round it out with pellets and frozen foods.

How big does a Pacific molly get?

An adult Pacific molly reaches about 2.8 in (7 cm).

How can you tell a male Pacific molly from a female?

Males stay somewhat smaller than females.

How does a Pacific molly breed?

A Pacific molly is a livebearer and breeds readily, often producing large broods of 20 to 60 young. Some adults eat fry, so give the young plenty of cover.

Related species