2025 Volume 81 Issue 16 Article ID: 24-16206
One of the conditions for a fish-friendly river is the provision of shelter, and one method of securing shelter for fish is the installation of fish nest blocks. Various studies have been conducted on fish nest blocks, and it has been found that fish nest blocks are useful as resting places for fish when they become fatigued and as shelter from external factors. In this study, the effects of aperture shapes (full open, upstreamopen, downstreamopen, top open, and bottom open) and velocity divided by body length (3, 6 and 9 (1/s)) on the resting characteristics of Plecoglossus altivelis, Opsariichthys platypus and Nipponocypris temminckii were examined. As a result, in the case where the aperture was secured on the bottomside, it was found that fishes can enter the fish nest block easy, and quickly. Spending time in the full open and bottom open fish nest blocks is longer than that of another one.
