Effect of copper on Tilapia nilotica L. 1758; uptake and mortality

22 6. SUMMARY EHPECT of COPPER on Tilapia nilotioa {ft) 1758 5. UPTAKE and MORTALITY Effects of copper on accumulation and mortality of Tilapia nilotioa were tested git a range of concentrations (0.1, 1.0, 5-0, 10.0, 50*0 100.0 and 200.0 ppm) over periods from 1 to 60 days. The amount of copper accumulated by the fish tissue increased with increasing time of contact with a particular Cu solution and with increasing Cu concentrations. In a given concentration, no difference was found "between the copper content of fishes which idled before a given period and those lived through the end of that period. Dead fishes accumulated about 30 pg Cu per g dry weight. In lower concentrations (eg. 5*0 ppm) no fish was dead "by the end of 60 days period hut the amount of copper accumulated was the same as with the dead fish. There was no mortality in the 0.1, 1.0 and 5*0 PP11* copper concentrations and in control aquariums during the 60 day period. 100 $ mortality was observed in 50.0, 100.0 and 200.0 ppm concentra tions in 15,' 7 and 1 days respectively. Tilapia I^q'8 ranged from 26 days in 10.0 ppm to less than 1 day in 200.0 ppm copper.