Redmouth Cardinalfish

The Redmouth Cardinalfish (Apogon erythrosoma) is a reef-associated marine species found in tropical regions. The genus name "Apogon" derives from the Greek words "a," meaning without, and "pogon," meaning chin or beard. The species name "erythrosoma" refers to its reddish coloration, originating from the Greek "erythros" for red and "soma" for body.

This species is characterized by distinctive red markings on its snout and gill plate. It can attain a maximum length of 3.8 cm, with the smallest female exhibiting mature gonads measuring 2.81 cm.

Morphologically, it features 7 dorsal spines and 9 dorsal soft rays, along with 2 anal spines and 8 anal soft rays. The Redmouth Cardinalfish is further defined by the following anatomical features: D VI + I,9 (where the second dorsal spine is 1.3-1.7 times the head length); A II,8; 11-12 (rarely 13) pectoral fin rays; 1½ scales situated between the lateral line and the base of the first dorsal fin; 4-5 + 12-15 gill-rakers with 2 + 9-12 developed rakers; and 8-9 ceratobranchial rakers. Its preopercle ridge is smooth, the edge of the posterior preopercle is serrated, and the angle and ventral part are crenulated and membranous. The anterior nostril is positioned closer to the upper lip than the posterior nostril, with a skin flap forming the dorsal edge of the first supraorbital pore ending laterally with a small notch beneath or slightly before the medial margin of the anterior nostril. This notch does not reach the base of the nostril’s tube, and the caudal-peduncle depth is between 2.0-2.9 times its length.

Geographically, the Redmouth Cardinalfish is distributed in the 🌊 Western Indian Ocean, notably in the 🌊 Red Sea and the 🇲🇻 Maldive Islands.