Effect of the Gill Fluke <i>Gyrodactylus</i> on Haematology of Infected African Catfish <i>Clarias gariepinus</i> in Culture

Abstract

This observational study was made on the African Catfish Clarias gariepinus to determine the effect of the gill fluke Gyrodactylus species on the Catfish haematological parameters in a culture environment. A total number of 120 fish samples were collected from small scale fish farms in Ibadan Metropolis. Fish were screened for parasitism with the gill fluke Gyrodactylus then separated into positive and negative samples. Twenty specimens were selected randomly from each group into Group A (twenty fish from those parasitized with Gyrodactilus selected in one chance in two) and Group B (twenty from those fish that had no gill fluke in one chance in three). Packed Cell Volume (PCV), Total Erythrocytes Count (RBC), Total Leukocytes Count (WBC), and the differential white blood cells count) of group A, were evaluated and compared with that of group B, using one way analysis of variance (ANOVA). The effect of the parasite on the PCV of infected fish was significant at 5% (L= 0.025), while there was no meaningful change on the values of the RBC, WBC, Neutrophils and Lymphocytes. It was observed that neutroplils and lymphocytes constituted the bulk of the circulating white cells both in infected and free fishes. There was no oesinophils however few specimens among the infected group had monocytes in response to parasitism with Gyrodactylus. A good number of infected fish were found to have spur cell in their erythrocyte pool which was most likely ascribed to the presence of the parasites. The presence of spur cell in the circulating erythrocyte could then be a rapid diagnostic tool indicating the presence of Gyrodactylus infestation from a blood film of the affected fish.

Keywords: Clarias gariepinus, gill fluke, haematology.