Increased stocking density causes changes in expression of selected stress- and immune-related genes, humoral innate immune parameters and stress responses of rainbow trout (Oncorhynchus mykiss).

The present study investigated the effects of various stocking densities on the health status (stress and immune responses) of rainbow trout (Onchorhynchus mykiss). Juvenile rainbow trout were acclimated, placed in circular tanks under stocking densities of 10, 40 and 80 kg m(-3) and reared for 30 days. The relative expression of genes involved in stress and immunity such as HSP70, LyzII, TNF-1α, IL-1β, IL-8 and IFN-γ1 in the head kidney was determined.