Work out aquarium stocking level instantly with clear inputs, formula shown and shareable results.
The classic rule allows about one centimetre of adult fish length per litre of water, so capacity is the volume divided by that rule and stocking is the current length against it. The rule is a rough guide because waste output scales with fish mass not length, so a single large fish loads a tank far more than several small ones of the same total length.
Capacity
supported fish length = tank litres / centimetres per litre
Stocking level
stocking % = current fish length / supported length x 100
supported fish length = tank litres / centimetres per litre. The classic rule allows about one centimetre of adult fish length per litre of water, so capacity is the volume divided by that rule and stocking is the current length against it.
The rule is a rough guide because waste output scales with fish mass not length, so a single large fish loads a tank far more than several small ones of the same total length.
Enter tank volume, combined adult fish length, stocking rule. The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.