The feeding habits of Zeusfaber Linnaeus, 1758 were studied by examining digestive tracts in I2 size classes of individuals. It is a stenophagus species which begins life feeding almost exclusively on zooplankton until it is about 80 mm long, then switches gradually from zooplankton to small demersal fish, and finally when > 140 mm switches to feeding exclusively on benthic and demersal fish. Mysids were the most important food component in Z.faber < 141 mm and Cepola macrophrhalmu (Linnaeus, 1758) in Z . fiber 140 mm. The switch to fish prey was followed by a greater body weight per unit length. Z . faber > 140mm selected primarily for smalland intermediate-sized C. macrophthalma (and to a lesser extent for Cullionymus maculatus Rafinesque-Schmaltz, 1810, Guidropsarus sp. and Trzgla Iyra Linnaeus, 1758). Our results suggested that the ratio of vertical to horizontal dimension of prey, the motion and coloration of prey as well as the visual capabilities and perceptual potentialities of 2. fuber may all in a synergetic fashion account for prey type and size selection and the positive relations found between the size of 2.faber and the size and variance ofits ingested prey. Possible co-evolutionary relationships between Z..faber and C. macrophfhalma are also discussed.