Occurrence of pathogenic bacteria associated with Clarias gariepinus in selected fish farms of Kumbotso local governement area of Kano state, Nigeria

Abstract

With the diminishing rate of natural fish resources globally, a reasonable percentage of fish and fish products supply now comes from aquaculture. However, quality production is highly required for sustainable demand and supply. It is in view of the aforementioned that this study was designed to examine the quality status of Clarias gariepinus in relation to pathogenic bacteria in two fish farms in Kumbotso Local Government Area of Kano State, Nigeria. 66 Clarias gariepinus with bodyweight 17g - 215g were randomly sampled from July to December 2012 followed by the isolation and identification of different pathogenic bacteria from skin and gill. A total of 132 samples comprising skin (1cm2) and gill (1g) were subjected to microbiological assays in the laboratory following standard procedures. Nutrient Agar, MacConkey Agar, Eoisin Methylene blue, Salmonella Shigella Agar and Blood Agar were used for isolation and maintenance of cultures during the study. Lactose broth, Brilliant Green lactose bile broth (BGLB) was used for the estimation of Escherichia coli Most Probable Number per 1cm² of skin and 1 gram of gill (MPN/ml and MPN/g). The highest mean of Aerobic Plate Count (APC) was 1.26 x 10⁴ cfu/ml while the highest mean of Escherichia coli MPN/1cm² was 8.75. Bacterial pathogens isolated and percentage occurrences in parenthesis were Escherichia coli (54.27 %); Stapholococcus aureus (22.48 %); Pseudomonas aeruginosa (10.85 %); Salmonella paratyphi (9.30 %) and Enterobacter aerogenes (3.10 %). There was no significant difference (χ2 = 3.42, P > 0.05) in bacteria isolates from the two fish farms. The result from this study indicated that the fishes were less contaminated with pathogenic bacteria, thus consumers are safe to eat fishes harvested from these farms since all the values are within the recommended limit of < 5 x 10⁵ cfu/g for APC and, 11 for Escherichia coli MPN/ml by International Commission for Microbiological Specification for Food (ICMSF, 2007).

Keywords: Fish farm, Clarias gariepinus, Microbiological assays, Pathogenic bacteria.