Aluminium and pH effects on some osmoregularity and haematological parameters of the acid-resistant American bullhead Ictalurus nebulosus (Le Sueur).

Physiological experiments performed with the acid-resistant fish Ictalurus nebulosus gave evidence that: 1) Na+-influx at high H+- and Al-concentrations increased, in contrast to acid-sensitive fishes, which decrease their Na+-influx in such conditions; 2) high external Ca++-concentrations have no beneficial effect on low pH and Al toxicity; 3) differences in populations from acid compared to circumneutral lakes disappeared when acclimated to the same soft water of low ionic content (pH 6.8).