Belted cardinalfish (Apogon townsendi) are tropical marine fish in the genus Apogon. They grow up to 6.5 centimetres (2.6 in) in length. Belted cardinalfish are found in the waters of the western Atlantic Ocean, off Central and South America, inhabiting caves and holes. They are pinkish-red on the dorsal side and yellowish-red on the ventral side. Their eggs are carried in the mouth of the adult as they mature.