Molly
Poecilia sphenops
A sturdy livebearer that needs hard water and plenty of plant food, and does well in slightly brackish conditions.
Key facts
- Body length
- 3.1 in without fins
- Minimum tank
- 26 gallons
- Group
- 3+
- Temperament
- Peaceful
- Care level
- 1 / 5
- Lifespan
- Not well documented
- Diet
- Spirulina and vegetable flakes, blanched spinach, micro pellets
- Origin
- Mexico to Colombia and Venezuela
- Hardier than73%
- Bigger than51%
- Calmer than68%
Water: their range vs yours
Molly tank mates
- Neon tetraGets along in shared water.Good mates
- Harlequin rasboraGets along in shared water.Good mates
- Fancy guppyGets along in shared water.Good mates
- Panda corydorasGets along in shared water.Good mates
- OtocinclusGets along in shared water.Good mates
- Cherry shrimpGets along in shared water.Good mates
- BettaGets along in shared water.Good mates
- Tiger barbGets along in shared water.Good mates
- Amano shrimpGets along in shared water.Good mates
- Black neon tetraGets along in shared water.Good mates
- Black widow tetraGets along in shared water.Good mates
- Blood parrot cichlidGets along in shared water.Good mates
- AngelfishAngelfish eats small fish: Molly.Risky
- Chinese algae eaterChinese algae eater attacks fish with a similar shape or colour: Molly.Risky
- Clown loachClown loach attacks fish with a similar shape or colour: Molly.Risky
- Convict cichlidConvict cichlid can eat young or small Molly; adults are big enough to be safe.Risky
- DemasoniDemasoni attacks fish with a similar shape or colour: Molly.Risky
- Firemouth cichlidFiremouth cichlid eats small fish: Molly (SF: 'may eat much smaller fishes').Risky
- Blue dolphin cichlidBlue dolphin cichlid can eat Molly: prey body depth 1.8 cm ≤ mouth 6.3 cm.Avoid
- Iridescent sharkIridescent shark can eat Molly: prey body depth 1.8 cm ≤ mouth 32.5 cm.Avoid
- OscarOscar can eat Molly: prey body depth 1.8 cm ≤ mouth 12.3 cm.Avoid
- SeverumSeverum can eat Molly: prey body depth 1.8 cm ≤ mouth 5.0 cm.Avoid
- African clawed frogAfrican clawed frog should only be kept in a single-species tank.Avoid
- Marbled crayfishMarbled crayfish should only be kept in a single-species tank.Avoid
How we check
The numbers the tank model uses for mollies: water as ideal and tolerated ranges, bioload from adult mass, space, flow and how they act on other species.
- Standard length
- 8 cm (SL)
- Adult mass
- 19.96 g
- Bioload at 25 °C
- 6.93 BU
- Min. water
- 81 L net
- Min. footprint
- 90 × 30 cm per group
- Group
- 3+ (best 5)
- Swims in
- top, middle
- Flow
- low
- Body / fins
- fusiform, normal fins
- Diet type
- omnivore plant
- Fin nipper
- none
- Sensitive to
- —
Sources: Seriously Fish: Poecilia sphenops · FishBase: Poecilia sphenops
Care notes
Mollies range from Mexico to Colombia and Venezuela and grow to about 3 inches. Aquarium forms such as black, dalmatian and lyretail are partly crosses with sailfin mollies.
Give a group of one male to two or three females a 20-gallon tank with hard water and regular vegetable foods. Adults eat their fry, and balloon mollies are bred with deformed bodies that cause swim bladder trouble.
Questions
What size tank does a molly need?
At least 26 gallons (81 litres of water after decor). Adults reach about 3.1 inches without fins.
How many mollies should be kept together?
Keep at least 3, ideally 5 or more: fewer feel exposed and hide or turn nippy.
What water do mollies need?
70–82 °F, pH 7–8.5 and 15–30 dGH. Mollies come from Mexico to Colombia and Venezuela.
How long do mollies live?
Not well documented with good care.
What fish can live with mollies?
Good tank mates include Neon tetra, Harlequin rasbora, Fancy guppy, Panda corydoras and Otocinclus. Each is checked both ways for size, fin nipping, temperament, territory and shared water.