Map of sampling locations. The fish picture depicts a representative of Cathorops. A: Puerto Concha, Maracaibo Lake, Zulia state, VE. B: Isla de Toas and Isla de San Carlos, Maracaibo Lake, Zulia state, VE. C: Guarico, Maracaibo Lake, Zulia state, VE. D: Gulf of Venezuela, Falcón state, VE. E: Clarines, Anzoátegui state, VE. F: Puerto la Cruz, Anzoátegui state, VE. G: Ciudad Bolivar, Bolivar state, VE. H: Río San Pedro, Montijo Bay, PA. I: Rio Santa Maria, PA. J: Rio Parita, PA. K: Rio Estero Salado, PA. L: Rio Hato, PA. M: Rio Chagres, PA. N: Puerto Caimito, PA. O: Gulf of Panama, PA. P: Pearl Islands, Casaya Island, PA. For additional information, see Tables S1 and S3.