AquaStocker

Free Aquarium Calculators & Fish Guides

Stock your tank with confidence — instant calculators, a 70+ species care database, and 200+ fish compatibility answers. No signup, built by fishkeepers.

Free Calculators

Fish Stocking CalculatorAdd fish by species and see if your tank is over- or under-stocked, with temperament, temperature and schooling warnings.Aquarium Volume CalculatorYour tank's real water volume in gallons and liters from length × width × height.Heater Size CalculatorThe right heater wattage for your tank volume and how cold your room gets.

Popular Stocking Guides

Best Fish for a 5 Gallon Tank11 species that genuinely fit a nano tank — no guesswork.Best Fish for a 10 Gallon TankBeginner-friendly stocking ideas for the most popular starter size.Best Fish for a 20 Gallon Tank52 community fish that thrive with room to swim.Best Fish for a 29 Gallon TankThe sweet-spot tank — centerpiece fish and full communities.Best Fish for a 40 Gallon TankBigger schools, bigger personalities — 66 fish that fit.Best Fish for a 55 Gallon TankBig-tank stocking, from peaceful communities to showpiece species.

Most-Asked Compatibility Questions

Can a Betta Live With Neon Tetras?The most-asked tankmate question — answered with the real reasons.Can a Betta Live With Guppies?Why this pairing often goes wrong, and when it can work.Can a Betta Live With Cory Catfish?One of the safest betta tankmates — here's why.Can a Betta Live With a Goldfish?Spoiler: don't — the full temperature and bioload breakdown.

Browse Everything

Fish Care DatabaseSize, temperament, temperature, pH and schooling stats for 70+ freshwater species.Compatibility CheckerLook up whether any two fish can share a tank — 200+ pairings.Build Your AquariumPlan a complete setup — tank, filter, heater, substrate and stocking — step by step.Aquascape GalleryReal planted-tank inspiration to plan your layout.Guide LibraryEvery care guide, stocking list and compatibility deep-dive in one place.