There was a lot of researches about classifying some pattern of living objects. Researcher tried to get some special patterns which appear in natural life, such as sound, marks,color, shape.etc.In this research, the fish-classification tool is investigated by using pattern recognition algorithm. Fish type is classified from its agility and swimming direction which measured indirectly from its ultrasonic reflectance pattern. Ultrasonic reflectance produced by schooling fish is extracted to some features and subsequently those features will be used to classify and determine the type of a fish.