Examination of Behavioral Traits of Monocultures and Polycultures of Two Different Trout Species (Oncorhynchus mykiss, Salmo trutta ssp.) at Different Ratios Depending on Various Factors

Abstract

: The present study aimed to determine both the effects of monocultures of rainbow trout (R) and brown trout (B) and polycultures (R 75%-B 25%; R 66%-B 34% and R 50%-B 50%) on behavior. In the study, the area used vertically by the fish in the tank, the mobility rate of fish in the tank, the rate of tendency of fish in eating as soon as they were fed, whether the fish test the feed, the interspecies feed competition, the time they start to take the first feed, the duration of the feed consumption of the fish and the feed area of the fish have been considered as behavioral evaluation criteria. The trout were monitored with a camera to determine their behavior. Considering all behavioral criteria, the best polyculture rate was determined as R 66%-B 34%. Brown trout were found to be more mobile and exhibit more relaxed behavior compared to other groups in polyculture. In addition, interspecies feed competition was mostly encountered in this group. As a result, in this study, in which two different trout species were monocultured and treated at different polyculture ratios, the main factor causing behavioral change in fish was found to be the different stocking rates of fish to each other in the same tank. Different rates applied in polyculture caused unpredictable changes in behavior in both species. The ratio of fish used in polyculture was found to be a considerable factor affecting the final product and their behavior for aquaculture.