The free aquarium toolkit we wish existed when we started fishkeeping — accurate stocking math, real species data, and honest compatibility answers.
Most new fishkeepers lose fish in the first few months for the same avoidable reasons: an overstocked tank, an aggressive species mixed with peaceful ones, the wrong temperature, or a tank that was never cycled. The information to prevent all of that already exists — it is just scattered across forum threads, out-of-date calculators, and pet-store advice that is often wrong. AquaStocker pulls it into one place: enter your tank, pick your fish, and get a straight answer before you buy.
Three calculators (tank volume, heater wattage, and a species-aware stocking estimate), a care database of 70+ freshwater species with adult size, minimum tank, temperature, pH, temperament and schooling needs, and a compatibility checker that answers 200+ “can X live with Y?” pairings. Everything runs in your browser — no account, no email wall, nothing stored.
Our species data is hand-curated from established aquarium references and cross-checked against multiple sources — not scraped wholesale or generated blindly. Public fish databases are frequently offline or inconsistent, so every entry is reviewed by hand. Compatibility verdicts come from comparing real requirements (temperature and pH overlap, adult size, temperament, and schooling behavior) rather than guesswork. We explain the full method on our data-sourcing page, and every estimate is clearly labeled as a planning starting point — your specific fish and setup always come first.
AquaStocker is built and maintained by a freshwater aquarist who has kept planted community tanks, bettas, and shrimp for over a decade — and got tired of giving the same advice over and over. It is an independent project, not a pet-store brand. Spotted a number that looks off, or want a fish or calculator we do not cover yet? Tell us — reader corrections and requests genuinely drive what we build next.
The tools are free and will stay that way. We cover hosting with a few clearly-labeled affiliate links (as an Amazon Associate we earn from qualifying purchases) and display advertising. Neither ever changes the data, the rankings, or the advice — see our privacy policy for exactly how that works.