Abstract:
Early developmental stages of fish are particularly sensitive to many contaminants in
water. For instance, heavy metals such as cadmium (Cd) affect many developmental
processes in fish. The present study was undertaken to investigate the effect of
cadmium exposure during embryogenesis and endogenous feeding stage of climbing
perch. Our results show that 24-h LC50 of cadmium for embryo and larvae were
0.931 µM and 45.68 µM, respectively. Embryos were later exposed to sublethal
concentration of cadmium (0.3, 0.7, 1.0, 1.3, 1.6 and 2.0 µM) to determine the
hatching success, time of hatching and type of physical malformations. Hatching
success was significantly reduced (p<0.05) in the treated group in dose dependent
pattern where significant differences were found at 1.0 µM and higher compared
with the control group. However, the time of hatching was not affected (p˃0.05).
Malformations in embryos such as imbalanced of perivitelline space, less swelling,
coagulated eggs, lack of tail, yolk sac oedema and undeveloped head and tail were
observed at cadmium concentrations of 1.6 and 2.0 µM. Egg diameter, yolk
diameter and perivitelline space area showed a significant difference between control
and exposed groups (p<0.05).
