Opisthonema medirastre Berry & Barrett, 1963
Middling thread herring
photo by BĂ©arez, P.

Family:  Dorosomatidae (Gizzard shads and sardinellas)
Max. size:  30 cm TL (male/unsexed)
Environment:  pelagic-neritic; marine; depth range 0 - 50 m
Distribution:  Eastern Pacific: Los Angeles, California to Sechura Bay, Peru. (Included in at least some accounts of Opisthonema bulleri and especially Opisthonema libertate which used to be the only Pacific species recognized).
Diagnosis:  Dorsal spines (total): 0-0; Dorsal soft rays (total): 13-21; Anal spines: 0-0; Anal soft rays: 12-23. Body moderately deep and compressed; posterior edge of gill openings with two clearly visible, fleshy, protuberances; gill rakers numerous, 41 to 69 on ceratobranchial (in fish longer than 14 cm total length); last dorsal ray elongated and filamentous; back gray-green with silver-white flanks and a black spot behind the gill slit followed by a yellow lateral strip (Ref. 55763). The filamentous last dorsal fin ray distinguishes it from members of any other eastern Pacific clupeoid genus. Separated from other eastern Pacific Opisthonema by having 41 to 69 lower gill rakers in fishes over 14 cm standard length.
Biology:  Usually found near shore, forming schools. Feeds on crustaceans and pteropods.
IUCN Red List Status: Least Concern (LC); Date assessed: 14 November 2019 Ref. (130435)
Threat to humans:  harmless
Country info:   
 


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