TOXIC AND TERATOGENIC EFFECTS OF COPPER SULPHATE ON THE DEVELOPING EMBRYOS AND LARVAE OF SILVER CARP, HYPOPHTHALM1CHTHYS MOLITRIXVAh. AT TWO TEMPERATURES

iualitative, quantitative, morphological, histopathological and scanning electron microscopy studies were combined to evaluate the effect of three different concentrations of copper sulphate (CUSO4) (0.15, 0.2 and 0.3 mg/1) on the embryonic development and newly hatched larvae of silver carp, Hypophthalmichthys molitrix (Valenciennes, 1844).) The general development was described briefly. The tail bud stage becomes visible after 32 hours of fertilization, while pharyngula stage becomes visible after about 40 hours. Severe defects during embryonic development arise in the
experimental groups. The rate of embryonic development was shorter at higher temperature in both control and metal exposed groups. Hatching started almost 15 hours earlier at 26° C than at 20° C. At both temperatures, as the concentration of copper in water increased the percentage of deformed larvae increased, comparing to that of the
control. At both temperatures, all normal larvae from copper sulphate exposure began dying gradually from the beginning of rearing. The survival rate of the deformed larvae was considerably lower. Copper sulphate that caused growth inhibition might have been related to under-developed swimbladder which impaired fish activity and feeding. The neurotoxic effect of copper sulphate on silver carp involves a retardation of neurological development of the superficially
located neuromasts on the head. The neuromasts which are segmentally arranged exhibits bi-directional polarity. Copper sulphate also caused inhibition of skeletal ossification which might have resulted from disturbance of ionic regulation. The malformations of the deformed larvae (vertebral curvature & locomotion) caused impairment of swimming and feeding. Copper sulphate becomes a strong toxicant in excessive concentrations (from 0.15 mg/1). Copper sulphate less than 0.3 mg/7 is considered to be suitable for the control of algae (algicide), in lakes, reservoirs and fish cultures (Stominska and Jezierska, 2000). We could also safely use this substance for killing bacteria and parasites in fish culture (Roberts and Beitinger, 1974).