Effect of cadmium on embryonic and larval development of climbing perch, Anabas testudineus (Bloch 1792)

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).