Abstract
In order to understand the swimming characteristics and swimming ability of demersal fish, swimming experiments were conducted using Goby (Gymnogobius urotaenia sp.) during the upstream river migration period. Our observations were as follows: 1) at a flow velocity of 17 cm/s and higher, Gobies adhered to the bottom using the suction cups on their ventral fins, and showed repeated advancement and adherence; 2) the body length of Gobies is between 3-4 cm, and their average swimming speed was found to be 56-107 cm/s, which is 16-31 times the body length; 3) a swimming-curve-formula defining the relationship between swimming speed and swimming time was obtained; and 4) at flow velocities of 44 cm/s and 53 cm/s, we frequently observed Gobies flowing down in exhaustion during advancement.
