I conducted a mark-recapture study of Siren lacertina and Amphiuma means for one year at a lake in north Florida and documented average individual movement, size class distribution, seasonal activity patterns, survival rates, and density estimates. I captured Siren lacertina more frequently in winter and A. means more frequently in spring. Recapture probabilities of both species were low, whereas survival rates and density estimates (1.3 salamanders/m² for S. lacertina, 0.28 salamanders/m² for A. means) were high. I recorded no individual movement of over 10 m for either species. Sirens and amphiumas are large, predatory generalists that can have substantial biomass in wetlands (233 g/m² and 44 g/m², respectively, at this study site), and therefore can impact many other wetland species. Thus, more attention must be focused on evaluating and monitoring their populations.