Despite years of studies, cleaning interactions between cleaner and host fishes are still not well understood. Relating density of cleaner wrasse with fish species richness, density and biomass across different geographic localities may help to better understand cleaner/host fish relationships. In this study, we explored the patterns of variation in cleaner wrasse densities among 3 regions of the Pacific. An increasing gradient of cleaner wrasse density was observed from Ouvea (West Pacific) to Tuamotu (Central Pacific). This increasing density followed a decreasing gradient in the density of other reef fishes. Within each locality, densities of cleaner wrasse were positively correlated with densities of reef fishes. In order to better understand the underlying influences on the density of cleaner wrasse, the densities of reef fishes were examined in relationship to fish body size, fish sedentary, territorial and mobile behavior, and gregariousness. We showed that there is no relationship between the density of cleaner wrasse and host fish sedentary, territorial or mobile behavior, but that there are positive relationships with both host fish body size and host gregariousness. We hypothesize that the positive relationships are closely linked with fish ectoparasite loads.