Pathological effects of Eustrongylides sp. larvae (Dioctophymatidae) infection in freshwater fish, Glossogobius giuris (Ham.) with special reference to ovaries.

Present study was conducted to investigate the pathological effects of Dioctophymatid nematode (Eustrongylides sp.) in the freshwater fish, Glossogobius giuris. It is bright red colored nematode, measuring 30-55.26 mm in length and 0.525-0.630 mm in width, was found encapsulated or free in the body muscles, swim bladder, liver, intestine and ovaries of host fish. The overall prevalence of parasite was 38.47 ± 18.234 % and high prevalence of 68.75 and 50.0 % was observed in month of November, 2008 and March, 2008 respectively i.e. maximum infection of parasite was during pre-spawning and post-spawning period. Only the ovaries of host fish were found infected with encapsulated larvae. Ovaries showed 11.2 ± 0.088 % of prevalence and 0.259 ± 1.176 of relative intensity. The gonado-somatic index and fecundity of infected fishes were observed to decrease as compared to the uninfected ones. The histo-pathological damage caused by parasites in ovaries is characterized by damaged and disrupted germinal epithelium, damaged oocytes showing the sign of necrosis, liquification of yolk globules and reduction in the formation of yolk. The present observation attributes towards the reduction in fecundity and further decline in the population of the host fish.