All fish / Poeciliidae

Sulphur molly

Poecilia sulphuraria

Also known as sulphur molly, sulfur molly, sulphur mollie, teapa molly

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This is a small, plain silvery to yellowish livebearer that lives only in toxic, hydrogen sulphide-rich springs in southern Mexico. It has an enlarged lower jaw, which helps it skim the oxygen-richer surface film. Specialist keepers and researchers keep it because it is a remarkable example of adaptation to extreme water and is threatened in the wild.

Care at a glance

Care level

Hard

Temperament

Peaceful

Adult size

4 cm

Temperature

25 to 30 °C

pH

6.5 to 7.5

Smallest tank

60 litres

Keep as

Group of 6 or more, more females than males

Diet

Omnivore: algae, biofilm, small live and frozen foods, quality flake

Swims

Top of the tank

Lifespan

2 to 3 years

Water

Freshwater

Wild range

Mexico: sulphide springs near Teapa, Tabasco (Grijalva basin)

Breeding

Livebearer: females give birth to small broods of fairly large fry after internal fertilisation. It breeds in captivity in stable, warm water, but broods are small and few people keep the species, so maintaining a line takes care.

Good to know

It is listed as critically endangered and its range is tiny, so buy only captive-bred stock and do not release fish. It is rarely sold and is easily confused with the related sulphur-spring Poecilia mexicana populations.