Atherinella argentea Chernoff, 1986 .

Longfin Silverside, Moon Silverside; Pejerrey, Plateadito.

Distribution: Global: Eastern Pacific Ocean; from Guatemala to western Panama; entering estuaries and littoral lagoons and ascending river courses; Costa Rica: (Atlantic), Ni, Te, Be, Ba, Ta, Pi, Tr and Co (Pacific), 0– 7 m.a.s.l., Per, Dia.

Occurrence and conservation status: Nat, LC.

References: Bussing (1987: 158, as Melaniris guatemalensis (Günther 1864) —missidentification; 1998: 237; brief description, including illustrations and an identification key, information on distribution, with a map, and ecology), Angulo et al. (2013: 995; listed, including taxonomic information and distributional data) and Robertson & Allen (2015: 2528; detailed description, including illustrations, information on distribution, with a map, and ecology).