Asymmetric Production Responses to Biculture in Recirculating Aquaculture Systems: Danube Salmon (Hucho hucho) and Rainbow Trout (Oncorhynchus mykiss)

Abstract

This study investigated the effects of 84-day biculture rearing of Danube salmon (Hucho hucho) and rainbow trout (Oncorhynchus mykiss) on their growth performance, feed efficiency (FE), survival rate (SR), organosomatic indices, and plasma biochemical parameters in a recirculating aquaculture system (RAS). Fish were reared in Danube salmon monoculture (HU100), rainbow trout monoculture (HU0), and biculture (HU50). Rainbow trout exhibited significantly improved growth performance, FE, and condition factor under biculture, whereas Danube salmon achieved higher weight gain (WG) and specific growth rate (SGR) in monoculture. Organosomatic indices were largely unaffected by treatment, while plasma biochemical responses differed between species. The results suggest that rainbow trout gained a competitive advantage under bicultural conditions, whereas Danube salmon exhibited reduced growth performance under the tested stocking ratio and feeding regime. These results suggest that rainbow trout gained a competitive advantage under bicultural conditions, whereas Danube salmon exhibited reduced growth performance. The study is also helpful in the practical implementation of the effective and profitable intensive aquaculture of these salmonid species, especially regarding the balance between the culture of Danube salmon and rainbow trout under a bicultural system.