The black prochilodus (Prochilodus nigricans) is one of the most landed scaled fish species of the middle and upper parts of the Putumayo River, in the tri-national area between Colombia, Ecuador and Peru. Despite its importance, biological information about this species is too scant to guide fisheries management in this portion of the Colombian Amazon. In this study, 10884 individuals were sampled in the fish markets of Puerto Leguízamo between 2009 and 2017. This sampling was used to document reproductive patterns, but also growth and mortality parameters from length frequency distributions. The size at which all fish were mature was 22 cm Ls, which should be the established as the minimum size of capture to ensure that all fish have had a chance to reproduce before being caught. Growth and mortality parameters indicated a slower growth in the Putumayo than in other Amazonian rivers and a relatively high exploitation rate.