Flow and stress acclimation both enhance predator avoidance in a common cyprinid fish

Abstract

I investigated the impact of flow and predator stress acclimation on the swimming performance and predator avoidance ability of juvenile qingbo Spinibarbus sinensis. The experimental subjects were acclimatized for 20 d to nearly still water (control), flowing water, or nearly still water in the presence of their natural predators. Fish housed in flowing water showed a significantly greater capacity for prolonged swimming, as suggested by their critical swimming speeds compared to those of the other 2 groups. The group acclimatized to predators reacted more quickly to a predator stimulus, but did not exhibit faster burst (indicated by fast-start escape response) or prolonged swimming speeds. However, both the group housed in flowing water and the group exposed to predators demonstrated significantly greater predator avoidance capabilities than the control group. Therefore, both treatments substantially improved predator avoidance capabilities, although, apparently, via different mechanisms. This result may have considerable importance in the development of optimal rearing conditions in hatcheries for fish that are destined to be released into the wild.