Aquarium stocking calculator and tank-mate checker
Enter your tank size and the fish you keep or plan to buy. The checker compares them against AquaLog's care data for about 200 species: tank size, group size, temperature, pH, hardness, water type and fish to avoid.
Result
No problems found in the care data. Add fish gradually and keep testing the water.
- Shared temperature
- 23–28 °C (73–82 °F)
- Shared pH
- 6–7.8
- Shared hardness
- 4–18 dGH
- Largest minimum tank
- 75 L
What the checker looks at
- Minimum tank size for each species, against the volume you enter. Not sure of your volume? Use the aquarium volume calculator.
- Group size. Schooling fish kept in too small a group are stressed and often hide or nip.
- Shared temperature, pH and hardness. The ranges every fish can live in, so you know what to aim for.
- Water type. Freshwater, brackish and saltwater fish can't share a tank.
- Fish to avoid. Each species' care guide lists fish that bully it, eat it or are bullied by it.
- Temperament. Aggressive species, and solitary fish kept in numbers, get a warning.
What it can't see
Your filter, plants, decor and the individual fish. Fish don't read care guides, so add new fish slowly and watch them for the first weeks. Test ammonia, nitrite and nitrate after each addition; see what aquarium water parameters mean and how to choose tank mates.
Starting out? The beginner freshwater fish and fish for small tanks lists are good places to pick from.
Common questions
How many fish can I put in my aquarium?
There is no reliable formula. The old one-inch-per-gallon rule ignores adult size, body shape and waste. Start from each species' minimum tank size and group size, add fish a few at a time, and let your water tests decide: ammonia and nitrite should stay at 0 and nitrate under about 20–40 ppm.
Which fish can live together?
Fish that share a temperature and pH range, have similar temperaments, need the same type of water, and are not on each other's list of fish to avoid. The checker compares all of these from AquaLog's care data.
Why doesn't the checker give a percentage stocked?
How many fish a tank can carry depends on the filter, plants, feeding and how often you change water, which a calculator can't see. Rather than guess, it reports what the care data can back up and leaves the rest to your water tests.
Does it work for saltwater tanks?
Yes, for the saltwater species in the care guide. It flags tanks that mix freshwater, brackish and saltwater fish. For coral tanks, check the reef-safe fish list as well.
More tools
Keep your tank's tests, water changes and costs together in AquaLog.