Effect of dietary administration of letrozole and tamoxifen on gonadal development, sex differentiation and biochemical changes in common carp (Cyprinus carpio L.).

The effect of letrozole and tamoxifen on the specific growth rate (SGR; % day(-1)), gonado-somatic index (GSI), total haemoglobin (g%), gonadal and serum protein as well as lipid, sex differentiation and 17ß-oestradiol levels were studied in sexually undifferentiated Cyprinus carpio fingerlings 30 days post fertilisation (30 dpf) for 60 days. Results showed decreased GSI with tamoxifen treatment whereas letrozole increased it. There were reduced protein, lipid, triglyceride and cholesterol levels after treatment with tamoxifen and letrozole during gonadal development. Tamoxifen (200mgkg(-1) feed) induced 82.5% masculinisation, whereas letrozole in the same dose produced 98.5% males. Gonadal 17ß-oestradiol significantly declined from 86.0±1.41pg per 100mg (control) to 45.5±1.94pg per 100mg with tamoxifen and 36.0±0.72pg per 100mg with letrozole treatment. Similarly, serum 17ß-oestradiol levels also decreased after tamoxifen and letrozole treatments. Testicular development in 37.8% of fish treated with tamoxifen and letrozole was found to be more advanced (spermatocytes) than in the control (spermatogonium); however, there was reduced ovarian growth and increased atresia. It was concluded that letrozole and tamoxifen both significantly affect sex differentiation and gonadal maturity in C. carpio leading to the production of sex-reversed males, yet the effect of letrozole was more potent.

Hazard assessment of metals in invasive fish species of the Yamuna River, India in relation to bioaccumulation factor and exposure concentration for human health implications.

Monitoring of heavy metals was conducted in the Yamuna River considering bioaccumulation factor, exposure concentration, and human health implications which showed contamination levels of copper (Cu), lead (Pb), nickel (Ni), and chromium (Cr) and their dispersion patterns along the river. Largest concentration of Pb in river water was 392 µg L(-1); Cu was 392 µg L(-1) at the extreme downstream, Allahabad and Ni was 146 µg L(-1) at midstream, Agra. Largest concentration of Cu was 617 µg kg(-1), Ni 1,621 µg kg(-1) at midstream while Pb was 1,214 µg kg(-1) at Allahabad in surface sediment. The bioconcentration of Cu, Pb, Ni, and Cr was observed where the largest accumulation of Pb was 2.29 µg kg(-1) in Oreochromis niloticus and 1.55 µg kg(-1) in Cyprinus carpio invaded at Allahabad while largest concentration of Ni was 174 µg kg(-1) in O. niloticus and 124 µg kg(-1) in C. carpio in the midstream of the river. The calculated values of hazard index (HI) for Pb was found more than one which indicated human health concern. Carcinogenic risk value for Ni was again high i.e., 17.02 × 10(-4) which was larger than all other metals studied. The results of this study indicated bioconcentration in fish due to their exposures to heavy metals from different routes which had human health risk implications. Thus, regular environmental monitoring of heavy metal contamination in fish is advocated for assessing food safety since health risk may be associated with the consumption of fish contaminated through exposure to a degraded environment.

Environmental monitoring and health risk assessment of African catfish Clarias gariepinus (Burchell, 1822) cultured in rural ponds, India.

Water quality monitoring of Clarias gariepinus culture ponds (n = 27) revealed poor physico-chemical conditions and metal contaminants in fish tissues (n = 324). Human health risk assessment for some heavy metal contamination delineated low risk in general except for Aluminium (Al), Iron (Fe) and Lead (Pb) which accumulated significantly (p < 0.05) high in tissues. Health risks values were 6.3 × 10(-3)-9.6 × 10(-3) for Al; 3 × 10(-3)-9.7 × 10(-3) for Fe and 1.15 × 10(-5)-9.3 × 10(-6) for Pb respectively suggesting that contamination of Pb particularly in ponds fed with chicken waste (CW) was posing high risks.