PROBLEM TO BE SOLVED: To provide a tailfin identification method in which a pattern of a tailfin is not a determination reference.SOLUTION: The invention is configured to: perform image processing of imaging (image file) of a fish body for calculating lengths in a vertical direction and in a horizontal direction when a head region, a fin region, and a head part of a trunk region are upper sides in plan view of the fish body； acquire coordinates of contour shapes 11, 21 of a head 1 and a fin 2 in plan view of the fish body； then, use, as an identification index, any of each ratio of a head horizontal length m1, a fin horizontal length m2, a vertical length m3 of a trunk 3 where a head length m0 is a reference, a coefficient of an approximate expression calculated by a least square method from contour shapes 11, 21, a constant amount of a calculated Hu moment, or a combination of them； and identify an individual by conformity of the identification indexes.SELECTED DRAWING: Figure 1COPYRIGHT: (C)2020,JPO&INPIT【課題】模様を判別基準としない錦鯉の個体識別方法を提供する。【解決手段】魚体の撮像（画像ファイル）の画像処理を行って、魚体平面視における頭部領域と鰭領域と胴体領域の頭部を上方とした場合の垂直方向及び水平方向の長さを算出し、また魚体平面視における頭部１及び鰭２の輪郭形状１１，２１の座標を取得し、頭部長さｍ０を基準とした頭部水平方向長さｍ１、鰭の水平方向長さｍ２、胴体３の垂直長さｍ３の各比率、或いは前記輪郭形状１１，２１から最小二乗法で算出した近似式の係数又は算出したＨｕモーメントの不変量のいずれか、または組合せを識別指標とし、当該識別指標の一致性によって個体を特定する。【選択図】図１
