Feeding behaviour was recorded to study the visual response of an ambushing piscivore, the mandarin fish, Siniperca chuatsi, to motion and shape properties of various preys. Among several live organisms tested, the live prey were most frequently stalked and attacked. Live shrimps were less frequently stalked and scarcely attacked and live dragonfly nymphs least frequently stalked and never attacked. No visual response of the mandarin fish has been observed to dead organisms. For the moving dead prey fish driven by an experimental device, the mandarin fish stalked and attacked most frequently the intermittently fast-moving (v gtoreq 10 cm/s) prey fish, stalked and attacked less frequently the intermittently or continuously slow-moving (v ltoreq 5 cm/s) prey fish, and stalked most frequently but scarcely or never attacked the fast continuously moving prey fish. For the intermittently slow-moving (v = 5 cm/s) artificial preys of 6 kinds of shapes (a,b,c,d,e and f), the mandarin fish stalked all of them at the rates of 0.50, 0.24, 0.25, 0.25, 0.70, and 0.90 times per minute per mandarin fish respectively. But mandarin fish only attacked the artificial preys of a kinds of shapes (a, e and f) and the attacking rates were 0.18, 0.45 and 0.67 times per minute per mandarin fish respectively. The eye of the mandarin fish can perceive the motion of preys within certain distance, which determines the relatively long-ranged stalking behaviour of the fish. But its eye can perceive approximate shape of preys only within a rather close range, which determines the short ranged stalking and attacking behaviour of this fish.