Studies of carp fry,Cyprinus carpio, showed that temperature elevation within the range of 18–26° C increases the mortality caused by lowering the pH of water. It was found that 26‐h acclimation in acidic water (mean pH 4.22) prolongs the survival of fish in water at pH 4.02–4.20. Carp fry obtained less oxygen in water at pH 4–0, as compared to pH 7–0. The differences–though insignificant–pointed to an adverse effect of acidification on the respira