Parasitic Fauna of Oreochromis niloticus and Tilapia aureusin Two Reservoirs on River Owena, Southwestern Nigeria

Abstract

The parasitic fauna of Oreochromis niloticus and Tilapia aureusof the family Cichlidaewas examined the Old Reservoir (OR) and New Reservoir (NR)between May 2010 to April 2012 in River Owena in Ondo State, Nigeria. Three hundred and twenty fish (320) at 20 pieces of each of the fish species were collected and examined (per season) totaling 160 pieces each, from Oreochromis niloticus (O. niloticus) and Tilapia aureus (T. aureus)for parasitic infection using standard methods. The results show that 84 males and 76 females were examined for O. niloticus while 55 males and 105 females of T, aureus were examined. However, 37 (44.05%) male and 57 (75%) females were infected in O. niloticus while 38 (69.09%) male and 38 (36.19%) female were also infected in T. aureus in the study area. The t-test between the number of infected fishes in the two reservoirs shows significant difference (P≤ 0.05) between the rate of infection in O. niloticus and T. aureus (t = 0.0003) in both OR and NR. The highest parasitic prevalence and abundance of 22.50% and 0.38 were recorded for Dactylogyrus spp. in O.niloticus with the highest parasitic intensity of 1.92 seen in T. aureus. The result also reveals that OR had the higher number of infected fishes (45), total number parasite observed(178) as against 34 and 120recorded for NR. The prevalence (56.25%), intensity (3.96) and abundance (2.23) were also high for OR as against 42.50%, 3.53 and 1.50 respectively for NR.The multiple infections recorded in the fish specimens from the two reservoirsare indication of the rich parasitic fauna of the reservoirs. It is therefore recommended that proper management of the reservoir should be adopted to reduce the occurrence of parasitic fauna of the sites which will reduce the possible transmission of parasites from fish to humans.