Molly
Poecilia sphenops
Also sold as Mollies · Mollie
Synonyms Black molly · Sailfin molly · Balloon molly · Lyretail molly · Common molly · Mollienesia sphenops
Molly (Poecilia sphenops) is a peaceful freshwater fish that reaches about 10 cm (3.9 in) and swims in open water. It wants 75–82°F (24–28°C) and pH 7.5–8.5, is kept in groups of 3 or more, and needs a tank of at least 80 L (21 gal).
Check a freshwater stocking selection with your tank size and animal counts.
At a glance
| Type | Fish |
|---|---|
| Adult size | 10 cm (3.9 in) |
| Minimum tank | 80 L (21 gal) |
| Group size | 3 or more |
| Temperature | 75–82°F (24–28°C) |
| pH | 7.5–8.5 |
| Temperament | Peaceful |
| GH | 15–30 |
| Lifespan | 3–5 years |
| Eats shrimp | Yes |
Color forms · Same species, different color. Care is the same for all of them.
Before it goes in
- Molly needs at least 80 L (21 gal). The smallest size in this library that clears that is the 60H Tall.
- Keep 3 or more. Below that it hides, colours down and is far more likely to be picked on.
- It eats shrimp. Cherry Shrimp, Crystal Red Shrimp and Bamboo Shrimp are on the menu.
- It holds at 75–82°F (24–28°C). That shares a window with Betta and Cherry Shrimp, but not with Goldfish and Dojo Loach.
- It eats soft-leaved plants. Hygrophila corymbosa 'Siamensis' and Bacopa caroliniana will not last with it; tough-leaved Anubias nana 'Petite' and Marimo Moss Ball will.
- It grazes algae hard, which is most of the reason people buy it.
- A group of 3 takes up roughly 66% of what a 60H Tall will comfortably hold, so plan the rest of the stock around it.
Molly: care and setup
What tank size does it need?
At least 80 L (21 gal). The smallest size here that clears it is the 60H Tall.
How many should I keep?
3 or more. Fewer than that and it spends its time hiding instead of out in the open.
Will it eat shrimp?
Yes. Shrimp are food to it, so pick one or the other.
What water does it want?
75–82°F (24–28°C), pH 7.5–8.5, GH 15–30.
How long does it live?
3–5 years in a tank that suits it. That is how long you are signing up for.
Good tank mates
- Tank mates from this library that share its temperature window, are peaceful and eat neither it nor its young: Bristlenose Pleco, Celestial Pearl Danio, Otocinclus, Ramshorn Snail and Rummy Nose Tetra.
- Plants that hold up with it: Anubias nana 'Petite', Marimo Moss Ball, Subwassertang and Anubias barteri.