Free tool
Water-parameter interpreter
You tested the water — now what do the numbers mean? Enter your readings and get a plain-English read on whether your fish are safe, and exactly what to do next. Because a dying fish is nearly always a water problem: test, don't guess.
A reading, not a diagnosis. Targets here follow recognised welfare guidance (the RSPCA gives ammonia < 0.1, nitrite < 0.2, nitrate < 50 ppm). Test with a reliable liquid kit, and if fish are unwell despite good water, see the sick-fish guide. New tank? Read the nitrogen cycle. Sources:RSPCA,Aquarium Science.