Bacterial pathogens and indicators in catfish and pond environments

Abstract

Channel catfish (Ictalurus punctatus) fed a diet containing 26 or 38% protein with restricted and satiety feeding methods were examined for microorganisms on the fish surface and viscera. Water, sediment, and fish samples from the ponds were tested for fecal streptococci, fecal coliforms, Aeromonas hydrophila, and Pseudomonas aeruginosa, while fish samples were also analyzed for presumptive Listeria spp. (count on m-VJ agar) and psychrotrophic bacteria. There were no significant differences (P<0.05) in the fecal streptococci and fecal coliform counts for the water, sediment, and fish visceral samples. However, the aeromonad count for the visceral samples (4.20 log CFU/g wet weight) was significantly higher (P<0.05) than that of the water and sediments (2.40 log CFU/ml and 3.78 log CFU/g wet weight, respectively). Similarly, the P. aeruginosa count for the fish visceral samples was significantly higher (P<0.05) than that of the water and sediments. The mean presumptive Listeria spp. count for the fish visceral samples was 1.99 log CFU/g wet weight. Because of the higher bacterial concentrations in the fish viscera, it was concluded that cross-contamination of fish samples could occur during evisceration. Finally, the feed protein level and feeding method used in the ponds influenced the bacterial concentrations in selected sample types (i.e., water, sediment, fish surface rinse, or fish viscera).