The natural diet and prey abundance of the benthic coral reef hydrozoan Nemalecium lighti, a common tropical species, were studied by analysing the gastrovascular contents of polyps. Prey capture was estimated from 10 samples collected at 3-h intervals during a single diel cycle (12 September, 1995) in the San Blas Islands (Panama). Prey size ranged from 5 to 550 um, with invertebrate larvae being the main contributor to the diet of the species. Prey items were found in 56