Effect of the cyanide and heavy metal pollution passed in river Szamos andTisza on the aquatic flora and fauna with special regard to the fish

The authors summarise the living world's damage of the river Tisza and Szam os which was polluted by the bursting of a reservoir's dam. The dam belonge d to the company ,,Aurul", which mines precious metals near to Nagybanya in Roumania. The maximum cyanide concentration of the rivers decreased from > 30 mg/l to 1.49 mg/l, the quantity of copper was determinant among the toxi c metals found in the water. Because of the pollution about 127-1241 tons o f fish died. The pathological examination of different fish species did not show definitive pathological changes besides the flaming red colour of gil ls and blood which is characteristic of cyanide poisoning. The cyanide cont ent of the muscular system and gills was determined between 0.22-2.91 mg/kg and 0.4-3.3 mg/kg respectively. The increase of cupper was not justified. The taxons of microscopical an macroscopical flora and fauna were damaged i n radically different degrees but the examinations give us hope that the ec ological catastrophe did not cause enduring damage in the living world.