Microbiota of the aquatic environment and rainbow trout when grown in the RAS

Abstract

Fish production in closed systems is an intensive way of fish farming. However, keeping fish in plants with a closed water supply does not solve the problem of diseases in aquaculture facilities. The greatest damage is caused by bacterial diseases. In this regard, the study of the sanitary state of the aquatic environment of fish is relevant. The article provides information on the physicochemical parameters of water, the species composition of the microflora of the aquatic environment in the basin, microbiological indicators of the sanitary state of water, the total microbial count (TMC) and the number of bacteria of the E. coli group (BCGC) in the RAS when growing rainbow trout. Sanitary indicators of water quality in the pool, both in the first days of keeping rainbow trout, and after a week were within the normal range. There was only a numerical increase in the total microbial number and bacteria of the E. coli group in water samples taken after a week of finding the trout in the pools. According to the results of a study of the contamination of the skin and gills of rainbow trout, as well as the water in which it is contained, an increase in time was revealed from 69 to 73 CFU/ml on the skin and from 85 to 89 CFU/ml on the gills within a week. The qualitative composition of the microflora of the skin and gills of rainbow trout is represented by bacteria of the genera Aeromonas, Pseudomonas, Bacillus, Enterobacter, which is similar to the qualitative composition of the microflora of water. The study of the intestinal microflora of rainbow trout revealed that it also contains bacteria of the genera Aeromonas, Pseudomonas, Bacillus, Enterobacter. At the same time, lactic acid, streptococcal, staphylococcal bacteria, yeast-like fungi of the genus Candida were found, which are normal representatives of the intestinal microflora in small quantities.