Bolti (Tilapia niloticus) fish were grown in polluted water with one of the
heavy metals namely cadmium. copper or lead. The concentrations of the tested
metals in fresh water environment were 0.1 and 0.2 mg/l Cd, 0.25 and 0.50 mg/l Cu
and 0.1 and 0.2 mg/l pb. An experiment of 56 days was performed to study the effect
of the tested sublethal levels of each of cadmium. copper and lead on growth
performance. body composition. residual concentration and muscular and abdominal
area of fish body. A set of 140 fish with 10 g average initial body weight was divided
into 14 similar groups in glass aquaria containing 75 liter of water in each. The
treatments and the centrol were allocated to the experimental groups in doplicates.
The fish were fed on a commercial diet containing about 25% crude protein at a rate
of 3% of the body weight daily during the experimental period. The results showed
that cadmium. copper and lead caused a significant reduction in the average weight
gain (AWG). specific growth rate (SGR). survival rate (SR). feed conversion (FC).
protein efficiency ratio (PER). and carcass dry matter and protein percentages.
Residual concentration increased in fish tissues. Fish muscles area decreased at the
two levels studied of each pollutant as compared with the control.