Epibenthic marine fish populations were sampled in order to establish quantitative base-line data for use in long term monitoring of the northern Indian River lagoon system, Florida. Fish samples were taken by trawling monthly at 8 fixed stations from June through September, 1979 and 1980. Fifty-seven fish species representing 29 families were collected. The fish community was numerically dominated by a very few species. Anchoa mitchilli alone accounted for 87% of the 105,853 individuals collected. Abundance, domin ance, and species diversity were compared among the three lagoon subdivisions, Mosquito Lagoon, Indian River, and Banana River. Greater numbers of fishes were collected in the Indian River, while the highest diversity levels were in the Banana River. Although most species were collected in all three subareas, gross inequities occurred in the numbers of individuals taken. For example, Mosquito Lagoon produced significantly more Micropogonias undulatus and Leiostomus xanthurus than either the Indian or Banana rivers. Significantly more Syngnathus scovelli and Anchoa mitchilli were collected in the Indian River than in the Banana River, and the Banana River produced significantly more Lagodon rhomboides than the Indian River. The only measured environmental parameters that appeared to play significant roles in determining fish populations were vegetative cover and salinity. An importance value (IV) index, combining relative abundance, relative frequency of capture, and relative size (biomass) per individual, was calculated for each species in the community. Dominance ranking by IV has advantages over dominance ranking by relative abundance alone and is calculable for making comparisons in a long-term monitoring study.