Family: APOGONIDAE, Cardinal Fishes

FAMILY APOGONIDAE

CARDINAL FISHES

Cardinalfishes are small (< 15 cm); body oblong, laterally compressed; large eyes; a moderately large oblique mouth that opens at the front; top jaw wide, partly concealed when mouth is closed, scaleless, no extra bone above rear jaw bone; preopercle with serrated rear edge and a smooth ridge in front of margin; opercle without spines; two separate dorsal fins, VI + I, 9; anal fin II, 8-9; scales large, rough to smooth, 23-45 with lateral line tubes; lateral line complete, extends onto base of tail fin.

The name cardinalfish comes from the red color of many of the species. Cardinalfishes occur in a diversity of habitats, but individual species are restricted to relatively narrow ecological zones. Most prefer caves and crevices of rock or coral reefs. At dusk they emerge from these retreats for nocturnal feeding. Most species are seen as solitary individuals, in pairs, or in small aggregations. However, some eastern Pacific species form dense aggregations near the reef"s surface. Cardinalfishes are one of few marine fish families in which oral brooding is found. During spawning the female releases a large gelatinous egg mass containing up to several hundred eggs. The mass is summarily fertilised by the male who then engulfs it with his mouth. Egg brooding males are easily distinguished by their swollen throats and the eggs can clearly be seen when the mouth is partially opened. Incubation lasts several days, during which time the male is unable to feed. Its main activity consists of periodically juggling the position of the egg mass. Most consume some form of zooplankton (often copepods), and small benthic invertebrates such as crabs and shrimps are also eaten.