Microbiological studies of carp (Cyprinus carpio L.) fingerlings wintered in cooling waters

The study was carried out in the winter of 1999/2000 at the fishing base of the Olsztyn Fishing Farm (Poland). The base was comprised of 48 fish cages (15 m super(3) each) suspended in a post-cooling water canal of the Ostroweka thermal-electric power station. During the 190 days of observations (31 October 1999 -- 15 May 2000), the following factors were analysed: bacteriological contamination of skin, muscle and gastric contents of carp (Cyprinus carpio fingerlings produced in cages from summer fry (July fry; 3-5 g body weight). Bacteriological analyses consisted of determining the total count of bacteria cultured on agar (TVC 20 degree C and TVC 37 degree C), the total count of colic bacteria (Escherichia coli) on Endo medium (Enterobacteriacea) and bacteria that is potentially pathogenic to fish and humans (Aeromonas hydrophila, Pseudomonas fluorescens, P. aeruginosa, Staphylococcus aureus). The identification of microorganisms was carried out using the biochemical tests Api 20 NE, Api 2E and Api Staph (bioMerieux). Statistical analysis showed significant differences in the number of all the bacteria assayed between the muscle tissue versus digestive tract and skin mucus. The counts of all the groups of bacteria determined in the carp were permissible and did not exceed Polish hygiene norms.