TankBud

Southern molly

Poecilia vivipara

Also known as Vivipara molly

FreshwaterFish

Southern molly (Poecilia vivipara)
The Wet Spot Tropical Fish · Used with permission

Care at a glance

Temperature
72–81°F
22–27°C
pH
7.0–8.2
Adult size
3.1 in
8 cm
Minimum tank
20 gal
75 L
Temperament
Peaceful
Social behavior
Social
Swim level
Middle
Diet
Omnivore
Difficulty
Medium
Breeding
Livebearer · Easy
Rarity
Rare
Family
Poeciliidae
Origin
Atlantic South America, Venezuela to Argentina

Overview

The southern molly is a hardy, adaptable livebearer for the middle of a hard-water community tank. It is a step up from the easiest fish.

Did you know

The everyday aquarium guppy and the popular mollies sit in the same genus, Poecilia. The southern molly is the type species on which that genus is based.

Caring for the southern molly

Southern mollies do well as a colony, and a female-heavy group keeps courtship from focusing on any single fish. Give a colony a tank of 20 gal (75 L) or larger. They keep to the middle water and stay active, so leave open room between plants.

Keep the water hard and warm, at 72 to 81°F (22 to 27°C) and a pH of 7.0 to 8.2, with good filtration. They hold condition best in fresh, mineral-rich water. They handle a little added salt easily but do not need it.

Feed them as omnivores with a strong plant component. Offer algae and spirulina, blanched vegetables, flake, pellets and frozen foods.

Southern mollies are peaceful and get on with other tough, hard-water community fish. Very small or timid species suit them less well.

Females give birth to live young rather than laying eggs. Breeding them is easy, and they produce broods readily in a mature aquarium.

Good to know

The southern molly, Poecilia vivipara, was named by Bloch and Schneider in 1801, in the same work that established the genus. Its species name, vivipara, reflects its live-bearing habit. It sits in the large livebearer family Poeciliidae.

In the wild

The southern molly lives along the Atlantic coast of South America, from Venezuela to Argentina. It is found in coastal fresh and brackish waters, including lagoons that can turn quite salty.

Weekly picks

Tank mates

The southern 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 southern molly need?

A southern molly needs at least 20 gal (75 L). It spends most of its time in the middle.

What temperature and pH does a southern molly need?

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

What does a southern molly eat?

A southern molly eats like an omnivore with a strong plant component. Feed it algae and spirulina, blanched vegetables, flake, pellets and frozen foods.

How big does a southern molly get?

An adult southern molly reaches about 3.1 in (8 cm).

How does a southern molly breed?

A southern molly gives birth to live young rather than laying eggs. Breeding it is easy, and it produces broods readily in a mature aquarium.

Related species