A production function for cage culture of Pagrosomus major was estimated by data from a survey of producers in Huiyang county, Guangdong province during 1985-1986. Explanatory variables in the quadratic model included stocking density, fingerling size, length of growing season, feed coefficient, squared and cross product terms. Model R 2 was 82.8%. Profit maximizing stocking densities were calculated for varying levels of growing season duration, fingerling size, fingerling price and adult fish price.