Molly vs Platy
Two hardy, colourful, hard-water livebearers for a peaceful community. The molly is a bigger, algae-grazing character; the platy is a compact, easy-going all-rounder. Here's which fits your tank.
The quick verdict
Both are peaceful, beginner-friendly and want hard, alkaline water, so it comes down to size and space. Choose the platy for a smaller tank, easy upkeep and huge colour variety. Choose the molly if you have 75 litres or more and want a larger grazer that helps keep algae down. They also live together happily.
| Molly | Platy | |
|---|---|---|
| Care level | Beginner | Beginner (very easy) |
| Min tank size | 75 L / 20 gal | 54 L / 14 gal |
| Temperament | Peaceful | Peaceful |
| Adult size | 6–10 cm (bulky) | 4–6 cm |
| Water | Very hard, pH 7.5–8.5 | Hard, pH 7.0–8.0 |
| Best for | Bigger tanks, algae grazing | Smaller tanks, easy colour |
The real differences
Size and mess again. Platies are compact and undemanding, thriving in 54 litres and tolerating a wide range of hard water. Mollies are noticeably larger and bulkier, produce far more waste, and want even harder, more mineral-rich water — soft water leaves them prone to health problems. Mollies also lean more herbivorous, spending the day grazing algae, while platies are easy omnivores that also nibble soft algae. Both breed steadily, so plan for fry.
Which should you buy?
Our pick
For a first tank or anything under 75 litres, the platy is the more flexible, lower-fuss choice. If you have the space and filtration and want a bigger grazing fish, the molly brings real character. Read the molly care guide and platy care guide, or start with our best beginner aquarium picks.
Frequently asked questions
Are mollies or platies easier for beginners?
Platies edge it. They stay small (4–6 cm), settle happily in a 54-litre tank and are a touch less messy. Mollies are just as hardy but larger (6–10 cm), heavier waste producers that want at least 75 litres and want very hard, mineral-rich water. Both are excellent, forgiving livebearers.
Can mollies and platies live together?
Yes. They are both peaceful, hard-water livebearers and mix well in a tank of 75 litres or more. The main thing to watch is that mollies grow much larger, so give the tank enough room and filtration for the bigger fish.
Do mollies and platies interbreed?
No — they are different genera (Poecilia and Xiphophorus) and do not cross. Platies do interbreed with swordtails, and mollies with other mollies, but a molly and a platy will not produce hybrids.
Found your model? Buy it at the right price.
UniverTrack tracks the real price of your aquarium gear across several retailers, spots fake discounts and warns you when it's genuinely the right moment to buy — with an AI assistant to guide you.