Fish balances flow resistance and high pressure in stagnation area

Fish attempt to optimize their swimming performance within their environments to minimize energy consumption. In this study, we conducted experiments using the Japanese dace (Tribolodon hakonensis), a simple flat plate, and a flume tank to simulate the swimming behavior in which fish exploit the stagnation area of the flat plate for maintaining their position. Two observed cases were: the fish localized by straightening the tail fin along the flow and by bending the tail fin like a cambered wing. The results of drag and lift forces suggest that fish adaptively flex tail fin based on the flow field, and selectively choose the optimal swimming posture for maintaining position.