An investigation on the effects of juvenile rainbow trout (Oncorhynchus mykiss) and brook trout (Salvelinus fontinalis) monoculture and duo-culture farming in freshwater and seawater on growth performance

The objective of this study was to compare growth performance and feed conversion ratios of rainbow trout (Oncorhynchus mykiss) and brook trout (Salvelinus fontinalis) juveniles in monoculture and duo-culture in freshwater and seawater under aquarium conditions. The fish were about 2-months old hatchery-reared brook and rainbow trout with initial weights of 0.934±0.033 (n=360) and 1.014±0.019 (n=360) g, respectively. The juveniles were kept in 10 L aquaria. Each aquarium contained 40 fish: 40 fish from each species for monoculture, 20+20 (rainbow trout+brook trout) fish from each species for duo-culture. The fish were in 3 groups with three replicates in freshwater and seawater and 18 aquaria were used. At the end of the 45 day study; mean live weights of brook trout were 2.735±0.153 g, rainbow trout 2.925±0.262 g in monoculture and brook trout 2.354±0.186 g, rainbow trout 3.882±0.494 g in duo-culture in seawater, brook trout 3.088±0.085, rainbow trout 3.364±0.093 g in monoculture and brook trout 2.164±0.169, rainbow trout 3.948±0.124 g in duo-culture in fresh water. While there were similarities between brook trout and rainbow trout in monoculture groups in sea water and fresh water, some differences were realized in duo-culture (p<0.001).