Effect of dietary tryptophan and betaine on tolerance of Caspian roach (Rutilus rutilus caspicus) to copper toxicity

The present study investigated effects of dietary tryptophan (TRP) and betaine (BET) on copper (Cu) toxicity tolerance in the Caspian roach (Rutilus rutilus caspicus). The Caspian roach fingerlings were fed diets containing 0, 0.25 and 0.5% TRP or 0, 0.5 and 1 % BET and combination of TRP and BET. Specimens were exposed to Cu (0.8 ppm) after either 30 or 60 days feeding. Mortality was recorded in each treatment 48 h after the Cu exposure. TRP decreased significantly fish mortality. However, BET had no significant effect on fish mortality. Specimens fed on the diet supplemented with 0.25% TRP had the lowest mortality among the treatments. It is concluded that 0.25% TRP reduces mortality of Caspian roach during Cu exposure.