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Mollies and platies are among the easiest, most colourful fish you can keep. Like guppies, they are livebearers: they give birth to live young, and they'll breed in almost any healthy community tank.
Mollies vs platies at a glance
| Platy | Molly | |
|---|---|---|
| Size | 5–6cm | 8–12cm |
| Minimum tank | 60 litres | 100 litres |
| Temperature | 20–26°C | 24–28°C |
| pH | 7.0–8.2 | 7.5–8.5 |
| Water | Medium to hard | Hard; tolerate some salt |
Varieties
Platies: variatus, hi-fin, Mickey Mouse and neon blue.
Mollies: assorted, lyretail, dalmatian and balloon mollies. Balloon mollies have a compressed body and benefit from careful feeding to avoid swim bladder problems.
Tank setup
- Plenty of swimming space, with planted areas for cover. Our beginner aquariums suit platies well.
- Good filtration: mollies in particular produce plenty of waste. See external filters.
- Hard-water friendly plants such as vallisneria and anubias.
- Most UK tap water is already hard enough. In soft-water areas, a buffer or crushed coral raises hardness. Read pH, GH and KH Explained.
Feeding
Mollies and platies are omnivores that graze on algae. Feed a quality flake with plant content once or twice a day, plus occasional frozen foods. Mollies appreciate algae wafers such as Hikari Algae Wafers and blanched vegetables.
Males, females and breeding
Keep one male to two or three females so no female is harassed constantly. Males have a pointed anal fin (the gonopodium); females have a fan-shaped one.
Females give birth every four to six weeks. Adults eat fry, so dense plants or a breeding box help more survive. Feed fry crushed flake or baby brine shrimp.
Tankmates
Peaceful community fish: guppies, corydoras, bristlenose plecos, rasboras and larger tetras. Avoid fish that need very soft, acidic water.
Common problems
- Shimmying (wobbling in place) in mollies often points to soft water or poor water quality.
- Fin rot: see our fin rot guide.
- Overpopulation: plan for the fry, or keep single-sex groups.
