How many fish are allowed in an aquarium? This question is often asked by beginners. Unfortunately, the maximum number of fish is often ignored, so it ends in an aquarium that has far too many inhabitants. This overcrowding can stress fish or also strongly influence the water values, which in the worst case ends with the death of one or more animals.

But how can you determine the number of fish?
There is no completely correct method to calculate this, since other factors such as only the number of liters of the tank are also decisive, but there are two rules of thumb that can be concluded approximately the number of fish.

1cm fish length per 1l water

For example: 4 x 5cm (Corydoras) + 10 x 4cm (Red Neon) = 60cm fish length = 60l water needed

1cm fish length per 30cm² bottom area

For example: 4 x 5cm (Corydoras) + 10 x 4cm (Red Neon) = 60cm fish length = 1800cm2 floor space
A normal 54 or 60l aquarium has a floor area of 1800cm2 (60cm * 30cm)

With the fish length it is absolutely to be considered that the size of an adult animal is taken!