This report is about six species of Rotifers belonging to three families follow: Brachionidae: three species of the genus Brachionus and one of the genus Platyias; Lecanidae: one species of Lecane, and Testudinelidae: one species of the genus Filinia. The report attempts to show how these species vary in quantity over a specified period according to the very considerable ÿchanges salinity in the Ciénaga Grande. Also indicated is the occurence of other genera of Rotifers in this region of Colombia.