Atherinella beani

Common Name

Bean's Silverside

Year Described

Meek & Hildebrand, 1923


Dorsal Fin: II-IV (mostly IV); I, 7-9
Anal Fin: I, 19-23
Pectoral Fin: 12-14
Lateral Line Scales: 37-40
Predorsal Scales: 19-22
Circumferential Scales: 17-19
Transverse Scale Rows: 6
Gill Rakers: 24-28
Vertebrae: 37-39

Body elongate, flat dorsally, and compressed laterally, with two dorsal fins. Eye large. Mouth terminal, strongly oblique, and does not reach the orbit. Premaxilla protractile. Distal end of premaxilla expanded. Premaxilla lacks postmaxillary process. Teeth in both jaws. Mesopterygoid teeth present. Rostral sensory system present as pits and depressions. Dorsal fins well separated. Spinous dorsal fin origin behind anal fin origin (above anal ray 4-6) and soft dorsal origin above anal fin ray 12-14. Anal fin long. Well developed sheath present on basal half of anal fin. Pelvic fin origin well behind pectoral fin base. Axillary scale present (<half pelvic length). Pectoral fin relatively long and high on body. Caudal fin forked. Scales cycloid.


Body translucent with a greenish dorsum. Lateral stripe fairly thin (about a scale width or a third eye diameter) and more dark than silvery. Faint dark cross-hatching on the dorsum. Patches of dense melanophores on head, snout, dorsal fin base, anal fin base, and base of caudal procurrent rays. Dorsal and caudal fin dusky.


Maximum size to 82mm SL.


Known only from brackish estuaries.


Known only from two specimens from coastal Panama.


Chernoff, B. 1986. Systematics of American atherinid fishes of the genus Atherinella. I. The subgenus Atherinella. Proceedings of the Academy of Natural Sciences of Philadelphia, 86-188.

Other Notes

This is the only Atlantic representative of a clade that contains the eastern Pacific species A. argentea, guatemalensis, guija, pachylepis, panamensis, and serrivomer. (Chernoff, 1986). Given it’s relationships and rarity it is probably a relictual taxa that has survived on the Atlantic coast of Panama long after the closure of the Panamanian Isthmus.