Lutjanus erythropterus, the crimson snapper, crimson seaperch, high-brow sea-perch, Longman's sea perch, red bream, saddle-tailed perch, small-mouth nannygai or smallmouth sea perch is a species of marine ray-finned fish, a snapper belonging to the family Lutjanidae. It is found in the Pacific and Indian Oceans.

Taxonomy Lutjanus erythropterus was first formally described in 1790 by the German physician and zoologist Marcus Elieser Bloch with the type locality given as Nagasaki. The specific name is a compound of erythros meaning "red" and pterus meaning "fin", a reference to the red median fins.

Description Lutjanus erythropterus has a moderately deep body which has a standard length of around two and half times its depth with a steeply sloped head and a large eye. The knob and incision on the preoperculum are weakly developed. The vomerine teeth are arranged a crescent shape with no rearwards extension and there are no teeth on the smooth tongue. The dorsal fin contains 11 spines and 12–14 soft rays and the anal fin has 3 spines and 8–9 soft rays. The long pectoral fins extend to the level of the anus and contains 17 rays. The caudal fin is truncate.