Comparisons of mensural and meristic characters of populations of Neetroplus nematopus Giinther from Nicaragua and N. fluviatilis Meek from Costa Rica revealed them to be conspecific. The only differences between these two nominal species are that the Costa Rican fish tends to have a lower profile and a more terete body shape, probably in response to a primarily riverine existence. Neetroplus fluviatilis is subsumed into N. nematopus. A third nominal species of Neetroplus, N. panamensis, was also examined and found not to possess the truncate incisor-like tooth structure which is the key character for defining Neetroplus. Apparently due to wear, the anterior teeth in adults of this species converge on the dental morphology of Neetroplus, resulting in taxonomic confusion. This species is removed from Neetroplus and referred to Cichlasoma; it becomes C. panamense (Meek and Hildebrand). Arguments, based on morphology and the overall pattern of cichlid speciation in Central America, are presented for the retention of Neetroplus as a valid monotypic genus.