It was obtained 355 individuals of Prochilodus magdalenae from local fisheries in Tumarado floodplain lagoons, low Atrato basin (Choco), Colombia located in Katios National Natural Park. Sampling was made along high water period in July-December 2004. Range of fish standard length was 190-380 mm; in spite of there were not significant differences in months, individual’s length was higher in December. Sexual ratio was different between months; female’s number was always higher. Mature individual abundance, gonadosomatic relationship, condition factor, and allometric coefficient suggest that reproductive period of P. magdalenae occurs between December and July. Oocites mean number by female was 52.698. Oocyte diameter showed high variation along sampling months. 22.25% of the fishes collected were under the permit minimum capture size.