ABSTRACT The results of the first experiment involving polyculture of mullet (Mugil incilis) and freshwater prawns (Macrobrachium acanthurus) in Colombia are presented. An experimental pond, having a surface area of 1.15 ha, was stocked with seed collected from the wild. Collection of seed and stocking of ponds were facilitated by the coincidental start of the dry season and the migration toward freshwater of mullet and freshwater prawns in February, 1976. One hundred and thirty three days after stocking the pond yielded 241 kg of prawns (210 kg/ha) and 340 kg of mullet (296 kg/ha). Macrobrachium acanthurus achieve an average weight of 12 g and Mugil incilis reached an average weight of 70 g. The pond was not fertilized and only 430 kg of supplementary feed, mostly consumed by mullet, was presented. The results obtained for prawn production in this preliminary trial are compared to those achieved by other workers with this species and with Macrobrachium rosenbergii.