Fishery statistics and length data series for Colossoma macropomum Cuvier obtained during 1992 and 1993 in the Lower Amazon, Brazil were used to describe the fishery and to estimate growth and mortality rates. Mean population parameters were L = 119.85 cm (total length), W = 33.4 kg, K = 0.228 year–1, C = 0.505, Winter Point = July, M = 0.445 year–1, F = 0.94 year–1 and Lc = 28.29 cm. Yield-per-recruit analysis showed that an excessive fishing effort and principally a very low length at first capture lead to an increase in overfishing in the region. Corrective measures are recommended.