Sex and Age-related Parasitism of <i>Clarias gariepinus</i> in earthen ponds in African Regional Aquaculture Centre, Aluu, Rivers State, Nigeria

Abstract

This study aimed at investigating the sex and age-related parasitic burden of Clarias gariepinus cultured in earthen ponds. Eighty–five (85) fish samples were selected randomly for analyses from three earthen ponds. Sexing was done by the observation of the urinogenital papillae. For parasitological analysis, skin and gill scrapes were taken for external parasites while the stomach and intestines were slit open, rinsed and observed for helminthic worms. Parasites identified included; Chilodonella sp. (0.3%), Ichthyophthirius sp. (41.1%), Trichodina sp. (55%), Icthyobodo sp., (1.0%) and Gyrodactylus sp. (2.4%). From the study 31 out of 56 males and 20 out of 27 females were infected with parasites. Prevalence of infection in males and females were 55.36% and 74.07% respectively. Mean intensity of parasites was also higher for females (150.75) than for males (62.68) Chi square analysis however, revealed no significant effect (p<0.05) of parasitism on gender. It was further observed that juvenile males and early adult females respectively, had more parasites with 55.3 and 92.4 parasite mean intensities. Among age groups, the mid juveniles (25-99g) (19%), late juveniles (100-299g) (65%) and early adults (300-500g) (14%) were most infected, although there was no significant effect (p<0.05). Sex-related prevalence could be based on hormonal changes and reproduction in females, and competitive search for mates by males. Age-related infection was predicated upon active feeding habits reported among fish of these ages It is therefore recommended that routine health checks be carried out for pond cultured fish. Furthermore, that older fish be sorted and kept together, as they would have stronger immunity than younger fish.

Keywords; Zoonoses, fish infection, late juveniles, earthen pond, Clarias gariepinus, sex, age