Yelloweyed Cardinalfish

Ostorhinchus monospilus

The Yelloweyed Cardinalfish is a reef-associated species found in the tropical waters of the Indo-Pacific region, including the Philippines, Indonesia, Papua New Guinea, and Australia. Divers can spot this fish at depths ranging from 2 to 41 meters, predominantly in coral reef environments. It is characterized by its compressed body shape and distinctive features, such as a whitish spot located behind the posterior base of the second dorsal fin. The fish has 8 dorsal spines, 9 dorsal soft rays, 2 anal spines, and 8 anal soft rays, with a maximum length of 7.8 cm. The roof of its mouth and portions of its gill arches are darkish, adding to its unique appearance. This species is nocturnal, often seen in pairs or groups during dives. It is a mouthbrooder, a reproductive strategy where the male carries the eggs in his mouth until they hatch. This behavior is typical of the family Apogonidae, to which it belongs. For divers, encountering the Yelloweyed Cardinalfish can be an intriguing experience, especially during night dives when the fish is more active. Its conservation status is categorized as Least Concern. Divers may find this fish in deeper waters within its depth range, where it prefers to reside.