Balloon Molly Breeding Guide (Poecilia sphenops var.)

Breeding the Balloon Molly, a selectively bred body-shape variety of the common molly (Poecilia sphenops): a livebearer with internal fertilization and broods of up to about 150 young.

Overview

The Balloon Molly is a selectively bred body-shape variety of the common molly (Poecilia sphenops); fish of the genus Poecilia have been selectively bred into many varieties. Like all mollies it is a livebearer: fertilization is internal and the female gives birth to free-swimming fry rather than laying eggs.

Sexing

Males have a gonopodium, a modified anal fin used to inseminate the female, and stop growing once it is fully developed. Females grow about 1 cm larger than males. Populations tend to contain more females than males.

Conditioning

Mollies mature quickly and breed readily; well-fed adults in good water reproduce on their own without special triggers.

Breeding Setup

Provide dense planting or floating cover. Because adult mollies, like other poeciliids, will eat fry that cannot flee in time, especially in cramped tanks, plants or a separate rearing space help newborns survive.

Spawning Behavior & Trigger

Males do not perform elaborate courtship; instead they approach females and force copulation. After internal fertilization the female carries the developing young to term.

Birth & Fry Care

Gestation lasts about a month, after which the female produces up to about 150 young; females in the genus typically give birth to a dozen or more fry every month. The newborn fry are free-swimming and can take finely powdered foods and newly hatched brine shrimp. Keep them away from adults to prevent cannibalism.

Common Challenges

The chief risks are fry being eaten by the adults and overcrowding from the species' rapid, frequent breeding.