The results of a systematic survey of species of monogeneans (Dactylogyridae) collected from the gills of pimelodid, poeciliid, cichlid, and characid fishes from the Atlantic coast of Nicaragua in 1999 are presented. The following species were recovered: Ameloblastella chavarriai and Aphanoblastella travassosi occurred on the gills of Rhamdia nicaraguensis; Salsuginus neotropicalis on Belonesox belizanus; Sciadicleithrum bravohollisae on Vieja maculicauda; Sciadicleithrum meekii on Archocentrus nigrofasciatus; Sciadicleithrum mexicanum on Cichlasoma urophthalmus, Parachromis dovii, Tomocichla tuba, V. maculicauda, and Parachromis managuense; Sciadicleithrum nicaraguense on Amphilophus alfari; and Palombitrema heteroancistrium, Urocleidoides costaricensis, and Urocleidoides strombicirrus on Astyanax fasciatus. Data on morphological and biometrical variability of individual species from different hosts are provided. Aspects of the zoogeographical distribution of the species found, which are mostly similar to those of southeastern Mexico, are discussed.