How Many Fish Fit in an Aquarium?

An aquarium is an enclosed ecosystem and can only healthily support a certain number of fish. Any waste produced must be either processed and neutralized or removed. If there are too many fish for the size of tank you have, wastes will build up more quickly than the tank can handle.

  1. Determining the Right Number of Fish

    • One commonly used method for determining how many fish your tank can handle is to allow 12 square inches of surface area per inch of fish. Calculate surface area by multiplying the tank's length and width. Then divide by 12 for the number of inches of fish you can fit.

    Fish Size

    • If your starting number is 32 inches of fish, there is a difference between having 16 two-inch fish and four eight-inch fish. Bigger fish need more room per fish and produce more waste.

    Temperaments

    • Some fish are good for a community tank. They will live in a school with others of their kind or are peaceful towards different species. Other fish are territorial or aggressive towards others; these fish prefer a lightly populated tank.

    Live Plants

    • Live aquarium plants help process and absorb the fish waste, so they will let you push towards the maximum number of fish.

    Warning

    • No matter the number of fish, a tank must be maintained with proper filtration and regular water changes.