Comparative study of the bacterial load and species diversity in the African catfish (Clarias gariepinus) cultured in contrasting aquaculture tanks in Uyo, Nigeria

Abstract

Comparative study on bacterial load and diversity on the intestine, skin and gills of cultured Clarias gariepinus from concrete and tarpaulin tanks were investigated. Determination of bacterial loads, species characterization and composition in fish parts were done using standard microbiological procedures. Results of the assay showed high bacterial count in intestine and gills of fish from both culture tanks. Heterotrophic bacteria count ranged from 1.7 x 10⁴ cfu/ml on skin of catfish cultured in tarpaulin tank to 2.6 x 10⁴ cfu/ml in gills of catfish from both systems, while the total coliform count ranged from 1.2 x 10⁴ cfu/ml in the gills to 3.9 x 10⁴ cfu/ml in the intestine. The Salmonella count was higher in the intestine of catfish in both systems, while the highest vibrio counts of 4.2 – 4.6 x 10⁴ cfu/ml was recorded in the gills of catfish from tarpaulin tank. In both culture systems, Pseudomonas, Salmonella and Escherichia coli, were not observed on fish skin. The Bacterial organisms isolated included: Escherichia coli, Salmonella enterica, Staphylococcus epidermidis, Vibrio anguillarum, Pseudomonas fluorescens, Serratia liquefaciens, Bacillus licheniformis, Shigella sonnei, Lactobacillus plantarum, Enterobacter aerogenes, Klebsiella pneumoniae and Proteus volgaris. S. epidermidis accounted for the highest frequency of occurrence (75.0 %) in concrete tank, while K. pneumoniae had the least frequency of occurrence (2.0 %) in tarpaulin tank. The bacterial flora recovered composed of potential pathogenic organisms of public health interest.

Keywords: Aquaculture, Bacterial load, Catfish, Concrete and tarpaulin tanks