Atlantic Molly

The Atlantic molly is a wild molly that, like the common molly (P. sphenops), has a short dorsal fin and an olive-gray body with rows of spots. Males are 6–7 cm, females around 10 cm. Some populations in southern Mexico live in toxic springs containing hydrogen sulfide and in caves that receive no daylight; because of their adaptations to these environments they are frequently studied in evolutionary research. It is one of the ancestors of the all-female Amazon molly.

• At least 100 liters and an 80 cm tank length for a small group.
• 24–27°C, pH 7.5–8.5, hard water; 1–2 g of salt per liter is optional.
• Tough-leaved plants along the edges, stones that grow algae, plenty of swimming space.
• 25–30% water change weekly.

An omnivore with a strong preference for plant matter. Spirulina flakes, algae wafers and blanched vegetables should be the staple, supplemented with frozen brine shrimp and daphnia.

Peaceful toward other species. Males display to each other with spread fins and chase the females persistently, so females are kept in greater numbers.

Good companions: platies, swordtails, Amazon mollies, rainbowfish suited to hard water, Ancistrus plecos.

Avoid: other molly species (hybridization), species that need soft and acidic water, fin-nipping barbs.