Fish kill caused by aluminium and iron contamination in a natural pond used for fish rearing: a case report

Contamination of Pansky Pond, in March 2013, with 119 mg/l aluminium, and 87 mg/l iron by acidic (pH 3.17) inflow from a nearby quarry caused fish die-off, while exhibiting symptoms of suffocation. Transformation of soluble forms of aluminium and iron into insoluble forms occurred on fish gill where the content of aluminium and iron was 100-fold and 12-fold, respectively, that found in control fish in an unaffected pond. In addition to insoluble aluminium and iron, gills showed presence of iron bacteria. Histopathology was characterised by expression of reactive processes and regressive alterations resulting in gill tissue necrosis. Impairment of the excretory function of gills was reflected in significantly (P < 0.01) higher concentrations of ammonia in the blood plasma of exposed fish compared to the control. Damage to parenchymatous tissues (kidney, liver, spleen) of the exposed fish was manifested as dystrophic alterations, higher aluminium and iron content, and enhanced activity of transaminases in blood plasma compared to the control.