CardinalsApogonidae

Cardinalfishes (Apogonidae) are generally small, often compressed fish, typically 5-15 cm (2-6 in) long, though some species reach 20 cm (8 in). They are characterised by notably large eyes, a prominent mouth, and two distinct dorsal fins. Many species display patterns of horizontal stripes, spots, or blotches on reddish, silvery, or translucent bodies.

During daylight hours, most cardinalfishes gather in dense aggregations within reef crevices, under ledges, or inside small caves, inhabiting depths from the shallows to at least 60 m (200 ft). They are primarily nocturnal predators, emerging at dusk to feed on zooplankton and small benthic invertebrates. Male cardinalfishes mouthbrood their eggs, holding them in their buccal cavity until hatching. Divers frequently encounter these aggregations in sheltered reef areas.