The main objective of the present investigation was to study the histopathological effects of paper mill effluent in the ovary of freshwater fish, Rasbora daniconius. In this experiment, we exposed the fish, Rasbora daniconius to lethal concentration at 9.5% (LC50 of 96 hrs) for 96 hrs and sublethal concentrations [1.9 % (1/5) and 0.95 % (1/10) LC50 of 96hrs] for 30 days. A second group of fish without exposure to paper mill effluent served as the control. The control ovaries appeared structurally normal. Ovaries of fish exposed to lethal concentration for 96 hr at 9.5% (LC50) of paper mill effluent showed different types of arteria in mature follicles, complete absorption of oocytes. Most of zona radiata are segmented and broken down in several sites. At 0.95% concentration of paper mill effluent for 30 days exposure showed thick ovarian wall, cytoplasmic clumping, cytoplasmic liquification and disappearance of nucleus were observed in mature oocytes. After 1.9% concentration exposure of paper mill effluent for 30 days, shows damaged oocytes, thickening of ovarian wall; cytoplasmic liquification and disappearance of nucleus in mature oocytes.

Feeding trial was conducted to evaluate the effects of dietary fucoidan supplementation on biological performance and bacterial resistance of early larval stage of Penaeus japonicus. Four microbound semi-purified diets containing graded levels of fucoidan (0.0, 100, 500, 1000 mg/kg diet) were formulated and fed to zoea larval stage of P. japonicus. Each diet was fed to three replicate groups of larvae and the feeding trial was terminated after the larvae had metamorphosed to the mysis stage. Results indicate that supplementation level of 500 mg fucoidan/kg diet is adequate to improve the zoea metamorphic survival to the mysis stage and this supplementation level was also found to be optimum in enhancing the bacterial resistance of zoea larvae against pathogenic Vibrio harveyi infection. The present results suggest that Undaria pinnatifida fucoidan at a dose of 500 mg/kg diet could be used as a dietary supplement to improve the metamorphic survival and enhance bacterial resistance of zoea larval stage of P. japonicas.

In the present study on Tighra reservoir, 40 species of fishes belonging to 23 genera, 12 families and 6 orders were identified. The order Cypriniformes was found to be a major order with 55.0% percent contribution. Siluriformes with 20.0%, Perciformes with 15.0%, Synbranchiformes with 5.0% and Osteoglossiformes and Beloniformes with 1.5% contribution follow the sequence. According to CAFF (2006), out of 40 species of fish, two species of fish are under endangered, eight species of fish under vulnerable, twenty species under lower risk near threatened, three species under lower risk least concern and four species were reported to be data deficient. Conservation steps of fish fauna in the Tighra reservoir have also been suggested.