In tropical estuaries, most fishes feed at different hours during the day. To determine the daily ration and consumption of the Ciénaga Grande de Santa Marta (CGSM) population of Anchovia clupeoides monthly samplings of a 24 h cycle were taken at the coastal lagoon between October 1995 and June 1996. A total of 4389 specimens were examined. The population of A. clupeoides consumes almost twice its weight per year, representing a 0.53% of its body weight per day. Though the CGSM presents a high primary production (990 gC/m2/year), the percentage that is transferred to the population of A. clupeoides is relatively low (0.055%). Hence, it seems that the high productivity of the CGSM is not being transferred to upper trophic levels due to the kind of fitoplankton, mainly cianobacteria.