Molly Care Guide
Poecilia sphenops · Easy care · 20 gallon minimum
Active livebearers that appreciate hard, slightly alkaline water and some vegetable matter in their diet.
Check your stocking with the stocking calculator →
How big does a molly get?
A molly (Poecilia sphenops) reaches about 4.0 inches as an adult. Plan tank size and tank mates around the adult size, not the small fish you buy at the store.
Tank size & setup
Give a molly a minimum of 20 gallons, with water at 72–80°F and a pH of 7–8.2. Keep them in groups of at least 3 — they are shoaling fish and become stressed and washed-out alone. As a easy-care, omnivore species, a stable, cycled tank with the right diet keeps them healthiest.
Good tank mates
Pair a molly with peaceful species that share its temperature and pH range. Compatible options include:
- Neon Tetra — 1.5", 10g min
- Guppy — 2.0", 10g min
- Platy — 2.5", 10g min
- Zebra Danio — 2.0", 10g min
- Corydoras Catfish — 2.5", 20g min
About the molly
Poecilia sphenops, called the Mexican molly or simply the molly, is a species of poeciliid fish from Central America. It was once understood as a widespread species with numerous local variants ranging from Mexico to Venezuela, but these variants are today considered distinct species belonging to the P. sphenops complex and P. sphenops itself as being native to Mexico, Guatemala, and Honduras. Due in part to its popularity as an aquarium fish, the species has been introduced outside of its native range, but many records may in fact refer to P. mexicana or other species from the complex. P. sphenops has been crossbred with other mollies, notably P. latipinna and P. velifera, to produce fancy mollies for the ornamental fish trade.
Recommended gear for mollys
As an Amazon Associate we earn from qualifying purchases.