The following parameter values are derived for a West Kalimantan (West Borneo) stock of the threadfin bream, Nemipterus marginatus : L infinity = 24.5 cm (L.T.), W infinity = 210 g, K = 0.42, t = -0.41 and M = 1.73. Yield-per-recruit for N. marginatus are presented. Catch per hour of N. marginatus is very low, even in the area of highest density ( approximately equals 3.5 kg/h at 45 m depth). Single-species exploitation of a stock of the type represented by N. marginatus appears unfeasible and the conclusion is reached that the traditional single-species approach in fish population dynamics--such as exemplified in this paper--does not help in formulating rational exploitation schemes.