The distributional responses of fishes to operation of a newly constructed power plant were assessed for indigenous populations of the Anclote Anchorage and River, Florida. Studies conducted during 1976 compared stations removed from potential plant effects with data collected from areas adjacent to plant intake and discharge. Comparisons were also made with preoperational information collected in the vicinity of the Anclote site. Beach seine collections exhibited a marked seasonal pattern related to the inshoreoffshore migration of nonresident species and the nursery function of the estuary. Abundance and species richness were greatest during the warmer months. as reported during preoperational surveys. Fishes at the shore zone station most affected by thermal discharges were more abundant during the coldest months and exhibited decreases during the hottest periods. This reversal of normally expected abundance was attributed to the thermal effluent. Comparable trawl and trammel net sampling conducted in the discharge canal revealed few species similarities when compared to collections over seagrass beds. The abundance and number of species in the discharge canal remained low during all but the colder months with collections dominated by sheepshead (Arc!losargus prohatocep! lalus). a species rarely taken over seagrass beds. The seagrass stations exhibited comparable catches except during colder months. when abundance and diversity were highest in affected areas. Noticeable decreases in summer collections at affected stations during 1976 were not recorded during baseline surveys. Suppressed summer diversity. though localized. was attributed to heat stress on the community.