Guppies and Mollies, side by side
| Guppy | Molly | |
|---|---|---|
| Adult size | 2 in5 cm | 3.9 in10 cm |
| Smallest tank | 10 gal38 L | 30 gal114 L |
| Keep | 3 or more | 3 or more |
| Temperature | 72–82 °F22–28 °C | 73–82 °F23–28 °C |
| pH | 7–8.2 | 7.5–8.5 |
| Temperament | Peaceful | Peaceful |
| Swims | Near the top | In the middle |
What size tank do they need together?
Each row shows how many of each the tank carries comfortably when these are the only two kinds in it.
| Tank | Guppy | Molly |
|---|---|---|
| 5 gallon | Too small for both | |
| 10 gallon | Too small for both | |
| 20 gallon long | Too small for both | |
| 29 gallon | 5 | 3 |
| 40 gallon breeder | 5 | 5 |
| 55 gallon | 9 | 6 |
| 75 gallon | 10 | 9 |
| 125 gallon | 17 | 15 |
Open this pair in the stocking calculator to add more fish or try your own tank.
How to make it work
- Add the calmer, smaller fish first, and the larger fish last.
- Use plants, wood or rocks to break up the view across the tank. Fish that cannot see each other all day fight less.
- Watch closely for the first week. Torn fins, hiding or a fish that stops eating mean it is not working.
- Keep a spare tank or a divider ready, so you can separate them the same day.
Questions and answers
Can guppies and mollies live in the same tank?
Yes, usually. Guppies and mollies like the same water: 73–82 °F (23–28 °C) and a pH of 7.5–8.2. Guppies spend their time near the top and mollies in the middle, so they stay out of each other's way.
What size tank do guppies and mollies need together?
At least a 29 gallon tank, which carries about 5 guppies and 3 mollies comfortably.
What temperature suits guppies and mollies?
73–82 °F (23–28 °C) suits both.
More pairs
- Guppies and bettas
- Guppies and neon tetras
- Guppies and fancy goldfish
- Guppies and angelfish
- Guppies and bronze corydoras
- Mollies and platies
- Mollies and tiger barbs
- Mollies and dwarf gouramis
- Mollies and cherry shrimp
- All pairs
Based on each species' adult size, water range and temperament (Seriously Fish, FishBase) and the rules of our stocking calculator. Individual fish differ: this is a guide, not a guarantee.