Assessment Of Fish Parasites And Determinant Factors In Some Earthen Ponds Of West Shoa, Ethiopia

Abstract

Fish culture is important in providing food for many people. However, it is under the influence of parasites, which impedes fish growth and reduces productivity. This research paper was, therefore, intended to assess the fish parasites and determinant factors in some earthen ponds of West Shoa, Ethiopia. A cross-sectional-based mixed research design, which engages qualitative and quantitative data collection approaches, was used to collect the primary data. Three different ponds located in various districts were selected purposely for the study. Water samples were collected from different depths, and a 2L composite was taken for physicochemical analysis. In addition, 75 fish samples (25 from each pond) of various sizes were randomly collected using mosquito nets. The total length and total weight of the fish were immediately measured using a measuring board to the nearest0.01cm and a sensitive balance to the nearest 0.01 g, respectively. The samples were transported to the Biology Laboratory, Department of Biology, Ambo University, and kept in an Icebox. In addition, an in-depth interview was carried out with the pond owners to determine factors aggravating the parasites. Water temperature was measured in-situ using a multiprobe meter, total phosphate was determined by calorimetric persulphate digestion, and nitrate content was determined by Brucine sulfate digestion using UV Vis. Spectrophotometer (Optizen POP, Korea). The length weigh relationship and condition factor of the fish were computed using the power function of TW=axLb and K = TW/TLb X100 respectively. The fish parasites were examined using naked eyes, hand lenses, a stereomicroscope, and a compound microscope. The parasites were identified to the possible general level using different identification keys. The results were subjected to SPSS software version 21.0 and analyzed by descriptive and inferential statistics (Chi-square and binary logistic regression). All the physicochemical properties of water showed a significant difference among the study sites (p≤0.05) except for total phosphate. The Ejersa Lafo pond had the highest water temperature (23+ 0.00oC), but the Ambo pond had the highest turbidity, DO, and total phosphate, accounting for 35.50+0.16 NTU, 8.43+0.06 mg/ L, and 7.53+1.96 mg/ L, respectively. Tokke Kuttaye pond, on the other hand, had the highest alkalinity (533.33+5.77) and Total Nitrate (5.90+0.042 mg/L). Of the 75 fish samples, 92% were tested positive for either internal or external parasites. The highest parasitic infestation (external and internal) was observed in Ejersa Lafo pond (64%) and Tokke Kuttaye pond (48%), respectively. Trichodinids were the most abundant external parasite identified in all the study ponds, whereas Diphyllobothrium was the most prevalent internal parasite. Skin is the outer part highly infested by fish parasites, whereas the intestine is the most widely infected internal part with internal parasites. Males and fish measuring 11-20 cm had a high parasitic infection. External parasitic infestation was inversely related to water temperature but positively related to DO content (p<0.05). In other words, internal parasites correlated positively with total nitrate (p<0.05). Food availability, water quality, and fish condition factors were the factors that aggravated the fish parasites. Generally, fish production was challenged with parasites at all of the study ponds, but the fish in the Toke Kutaye pond were more prone to the parasites than the other ponds. Therefore, extensive work is required to improve water quality and fish feed in order to boost their immunity.