CARACTERíSTICAS BIOLóGICAS DEL BLANQUILLO SORUBIM CUSPICAUDUS LITTMANN, BURR Y NASS, 2000 Y BAGRE RAYADO PSEUDOPLATYSTOMA MAGDALENIATUM BUITRAGO-SUáREZ Y BURR, 2007 (SILURIFORMES: PIMELODIDAE) RELACIONADAS CON SU REPRODUCCIóN EN LA CUENCA MEDIA DEL RíO MAGDALENA, COLOMBIA

some biological characteristics of pseudoplatystoma magdaleniatum and sorubim cuspicaudus were monitored during years 2004 and 2005 in the middle basin of the magdalena river, and we analyzed if they were synchronized with their larvae densities drifting in the magdalena river. we use data from 1245 adults of p. magdaleniatum and 1206 of s. cuspicaudus and larvae densities from water samples of the magdalena river. s. cuspicaudus reproduces in the ''low water'' hydro-period and p. magdaleniatum does during ''high water'' hydro-period. females were always bigger than males. lenght-weigth relationship was allometric and only the biologic characteristics of adults of p. magdaleniatum were associated with their larvae densities.