Aquarium stocking and equipment
How many fish fit by volume, filter and heater sizing, substrate amount
Fish species
Capacity
✓ fits
18 / 60 L
- Filter, L/h
- 180–300
- Heater
- ~60 W
- Substrate
- ~9 kg
The L/cm rule is simplified — liters per fish is better. Goldfish need ≥40 L for the first. Schooling fish must be kept in the stated numbers. Filter: 3–5 tank volumes/h; heater ~1 W/L; substrate ~1.5 kg per 10 L (4–5 cm layer).