Fish farm “Rajska dolina” Increased mortality -real scenario

On the owner of the farm reported to a colleague an increased mortality in rainbow trout fry. On we visited the farm and started the epidemiological investigation. The farm in operating with its own hatchery and water source and there is no record of movement of live fish into the farm.

Ten days ago the farmer noted increasing mortality in the fry which he started to treat with OTC (3 days) - increasing mortality and salt (3 days) resulting with a slightly decreased mortality. Ten day mortality fry (65%). Clinically, the fish were lethargic, anorexic with erratic swimming and light and dark pigmentation.

The gills were necrotic with gray patches, the body was decolorized, the gall bladder was full, yellow pigmentation of the intestine, hyperemic pyloric caeca, liver and spleen without changes. We took samples for laboratory examination. The farm is now under official surveillance and restricted movement was implemented.