Aquarium Stocking Calculator

Stocking a tank is limited by waste rather than by a rule of thumb, so this calculator asks what you plan to keep and works out what it costs the water. Enter the inside dimensions and the water depth, then each species by count and adult weight, or by adult length if that is what you know. It returns volume, surface area, filter turnover, the ammonia the fish produce each day, the nitrate that follows each week and the water change needed to hold a nitrate target. It will not tell you how many fish fit, because territory, shoal sizes and adult size cap a tank long before the chemistry does.

Calculator Type
Measured In

Enter the tank, then each species with the adult weight of one fish. Weight is the honest input, because waste follows body mass and food rather than length.

The depth of the water, not the height of the glass. For a careful figure that allows for glass thickness and substrate, use the aquarium volume calculator.
Rough adult weights: neon tetra 0.4 g, guppy 1 g, zebra danio 1 g, platy 3 g, corydoras 5 g, angelfish 25 g, common goldfish 150 g or more.
Adult community fish are usually fed 1 to 3 percent of their body mass a day. Growing fish and fry eat far more.
The figure on the box. Leave blank to skip the turnover line.
Ratings are measured with no media and no lift. Seventy percent is a fair working figure for a loaded filter.
Twenty is a common freshwater target. Reef tanks aim far lower, and hardy species tolerate more.
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Measured In

If you only know how big the fish get, give the adult length and a body shape, and the weight is worked out from the condition factor relation before the waste figures are calculated.

The depth of the water, not the height of the glass. For a careful figure that allows for glass thickness and substrate, use the aquarium volume calculator.
Applied to both species. Weight is K x length in cm cubed, divided by 100.
Adult length, in the unit chosen above, not the size in the shop tank.
Adult community fish are usually fed 1 to 3 percent of their body mass a day. Growing fish and fry eat far more.
The figure on the box. Leave blank to skip the turnover line.
Ratings are measured with no media and no lift. Seventy percent is a fair working figure for a loaded filter.
Twenty is a common freshwater target. Reef tanks aim far lower, and hardy species tolerate more.
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