Effects of Randomly Fired Underwater Currents as an Occupational Enrichment Program in Rainbow Trout (Oncorhynchus mykiss)

Occupational enrichment (OE) is directed at introducing variations in the tank water so that fish can exercise as they do wild. Two trials were carried out to test effects of randomly fired underwater currents (RFC) on rainbow trout (Oncorhynchus mykiss) maintained tanks a recirculation system, using 1226 distributed two independent trials. In Trial 1, fingerling (n = 6 tanks, n 40 per tank) classified into groups based low (13%) or high (30%) coefficient variation live weight (CV), and exposed RFC no (controls). 2, adult 12 20 either constant current (controls) from submerged pumps. Both lasted four weeks. No significant differences growth observed between treatments trial. similar CV throughout trial, while decreased controls. Also, plasma cortisol levels higher creatine phosphokinase (CPK) lower with initial CV. was trout, where also significantly triglycerides higher. The results suggest OE have positive by helping reduce stress levels, provides biologically meaningful environmental related natural history species.