About this stocking calculator
Use our online aquarium stocking calculator to plan freshwater tank stocking. It checks bioload, fish compatibility, and pH and temperature ranges. Explore freshwater species profiles for minimum tank sizes and temperament flags. It runs the same logic as leading fish tank apps like App-aquatic, with no sign-up required. New here? See how to use a stocking calculator, read about how stocking rules evolved from inch-per-gallon to bioload, or get the app to save tanks and track parameters.
Conservative by design. Our bioload calculation is deliberately cautious - based on years of fishkeeping experience and the science of bioload and tank capacity. Experienced keepers with strong filtration, plants and good maintenance can often exceed these limits; beginners may want to stock more lightly.
Stocking calculator FAQ
Is this aquarium stocking calculator free?
Yes - it's completely free with no sign-up or login required. Plan as many tanks as you like right here in the browser.
Is this a good alternative to AqAdvisor?
Yes. It uses the same bioload-and-compatibility idea but adds a fish compatibility matrix with plain-English reasons and a suggested fix for every clash, pH and temperature overlap, biotope matching and planted-tank adjustments - all on a modern, mobile-friendly interface. See the full AqAdvisor alternative comparison.
How many fish can I put in my tank?
Enter your tank size, filtration and planting and the calculator estimates a safe stocking level from litres, filtration turnover and plant uptake - using the same bioload engine as the App-aquatic app. See also how many fish per gallon.
Does it check fish compatibility?
Every pair of species is checked for temperament, predation, fin-nipping, adult size and overlapping pH and temperature. Conflicts show as caution or avoid with the reason and a suggested fix - the same engine behind our species care guides.
Is the stocking calculator accurate?
It mirrors the App-aquatic app's stocking and compatibility engine and errs toward safe, stable tanks. Treat it as a strong starting point and always monitor your own water parameters.
How many fish species does the calculator cover?
815 freshwater species, from common community fish like tetras and guppies to rarer imports - each with its own bioload, temperament, and pH/temperature range built in for accurate compatibility checks.