For most community tropical fish: ammonia 0, nitrite 0, nitrate under 20–40 ppm, pH 6.5–7.5, temperature 74–80°F, steady from day to day. Stability matters more than chasing a perfect number.
Targets
| Parameter | Target | Act when |
|---|---|---|
| Ammonia | 0 ppm | 0.25 ppm or more |
| Nitrite | 0 ppm | 0.25 ppm or more |
| Nitrate | under 20 ppm | over 40 ppm |
| pH | 6.5–7.5 (species vary) | a sudden swing |
| Temperature | 74–80°F tropical | outside the species’ range |
| KH | 3–8 dKH | under 2 (pH can crash) |
| GH | 4–12 dGH | species-specific |
Strips or liquid?
StripsQuick, fine for nitrate, pH, KH, GH. Readings are approximate.
Liquid kitMore accurate for ammonia and nitrite. Worth it while cycling.
Questions
How often should I test?
Every day while cycling or after adding fish; once a week in an established tank; any time fish act strangely.
Should I change my pH with chemicals?
Usually not. Most store-bought fish adapt to local tap water, and chemical swings hurt more than a slightly off pH. Pick fish that suit your water.
General information, not veterinary advice. Updated November 2026.