The Cardinal Fish is a mouthbrooder, where the males carry all the eggs in their mouth for weeks, unable even to eat until they have hatched. Normally the female will release an egg mass close to the chosen male and after the male fertilizes the eggs, he will take them into his mouth to carry them during the incubation period, until the fry are ready to hatch. As he incubates the eggs the male Cardinal Fish will open its mouth to rotate the egg mass from time to time, to keep them clean and aerated. At times it will partially expel the eggs before sucking them back in. It is estimated that up to 30 per cent of the eggs are accidentally eaten.
Photo credit: Nicolas Terry