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
Difficulty: Medium
Breeding: Easy
Rarity: Rare
Origin: Atlantic South America, Venezuela to Argentina
Family: Poeciliidae

Overview

A hardy, adaptable livebearer, the southern molly does well as a colony, and a female-heavy group keeps courtship from focusing on any single fish. It keeps to the middle water and stays active, so give it open room between plants. It is peaceful and gets on with other tough, hard-water community fish, while very small or timid species suit it less well. Feed it as an omnivore with a strong plant component: algae and spirulina, blanched vegetables, flake, pellets, and frozen foods. About 75 liters gives a colony the space it needs, and it holds condition best in mineral-rich water.

In the wild

Poecilia vivipara lives along the Atlantic coast of South America, broadly from the north of the continent down toward the south, in coastal fresh and brackish waters including lagoons that can turn quite salty. Keep it in hard, warm water, pH about 7.0 to 8.2 and 22 to 27 degrees Celsius, with good filtration and open swimming space. It handles a little added salt easily but does not need it in fresh, mineral-rich conditions.

Good to know

Poecilia vivipara is one of the founding species of the genus Poecilia, named by Bloch and Schneider in 1801, the same work that established the genus, and it is the type species on which the genus is based. It reaches about 8 centimeters and, true to its name, gives birth to live young rather than laying eggs, producing broods readily in a mature aquarium. It sits in the large livebearer family Poeciliidae.

Did you know

The everyday aquarium guppy and the popular mollies sit in this same genus, Poecilia. The southern molly is one of its earliest named members and helped anchor the group when it was first defined more than two centuries ago.