Microbiocenosis of cage farm rainbow trout in Northern Karelia

Unique features of the microflora structure characterize current physiological status of the fish farmed in cages and of their farming conditions. Whilst fish is in close contact with water, bacterial contamination of the fish external and internal organs depends on the quality and quantity of microorganisms around. The mass growth of aquatic saprophytic bacteria is a stress factor, and the fish spends its vital resources to fight it. Due to the adverse environmental conditions, the body resistance of the fish decreases and a variety of infectious diseases appear. For the first time, regularities of qualitative and quantitative distributions of microorganisms in the microbiocenosis of the rainbow trout and water pollution in some trout farms in Karelia are studied. It was established that the opportunistic bacteria of the genus Pseudomonas are dominant in the rainbow trout. Analysis of the fish microbiocenosis composition revealed how important are the obtained data. It also helped to substantiate their possible use as a screening test to detect changes in dynamic equilibrium of the fish bacterial flora and in natural aquatic ecosystems.