Thousands of flooded swimming pools were abandoned in greater New Orleans following Hurricane Katrina, creating novel larval habitats for mosquitoes. We conducted a randomized survey of 90 swimming pools in January 2006 to evaluate the extent of colonization by mosquito larvae and their predators. Most of these pools (71%) had not been drained, cleaned, or treated for mosquitoes. For the 64 non-maintained pools, 62% contained mosquito larvae, 92% contained predatory invertebrates, and 47% contained fishes. At the time of the study Culiseta inornata (Williston) (86% of all mosquitoes) dominated the collections. Also collected were Culex quinquefasciatus (Say), Culex salinarius (Coquillett), Culex tarsalis (Coquillett), and Anopheles atropos (Dyar and Knab). Anisopteran larvae were the most common invertebrate predators. Gambusia affinis (Baird and Girard) (76%) and Poecilia latipinna (Lesueur) (9%) were the numerically dominant fishes. The fish assemblage found in swimming pools was similar to that found in drainage canals that flooded the Lakeview area. Abundance and diversity of fishes were both negatively correlated with distance from levee breach. Fish, especially Gambusia affinis (Baird and Girard), appear to have strong negative effects on mosquito larvae and larger predatory invertebrates. Path analysis indicated that fishes exert a strong trophic effect on anisopteran and mosquito larvae in structurally simple swimming pools. No intraspecific trophic effects were detected. Introduction of local populations of G. affinis may be the most cost effective method of suppressing mosquito breeding in non-maintained swimming pools during restoration of New Orleans.