Toxicity of inorganic aluminium at spring snowmelt-In-stream bioassays with brown trout (Salmo trutta L.)

► Brown trout were exposed in situ to a gradient of pH and Ali in humic streams. ► pH above 5.0 and Ali below 20 μg/L sustain healthy brown trout populations. ► Low pH resulted in a tendency to decreased blood chloride levels. ► High Ali increased gill Al and haemoglobin suggesting that respiration was effected. ► The thresholds can be used to support liming strategies in recovering freshwaters.