Tony Wu / Banggai cardinalfish (Pterapogon kauderni) with hatchlings in mout, one of only two known fish species whose babies return to the parents at night, Lembeh Strait, North Sulawesi, Indonesia.

Pascal Kobeh / Golden cardinalfish / ring-tailed cardinalfish (Apogon aureus) under a hard corail table (Acropora ), Daymaniyat islands, Oman. Gulf of Oman.

Pascal Kobeh / Honeycomb moray (Gymnothorax favagineus) out of its hole with golden cardinalfish / ring-tailed cardinalfish (Apogon aureus), Daymaniyat islands, Oman. Gulf of Oman.

Franco Banfi / Shoal of Cardinal fish (Apogon imberbis) Ischia Island, Italy, Tyrrhenian Sea, Mediterranean

Franco Banfi / Painted comber (Serranus scriba) Ischia Island, Italy, Tyrrhenian Sea, Mediterranean

Franco Banfi / Cardinal fish (Apogon imberbis) with eggs in the mouth, Ischia Island, Italy, Tyrrhenian Sea, Mediterranean

Georgette Douwma / Moluccan cardinalfish (Ostorhinchus moluccensis) next to hydroids, brittlestars and sea squirts. Tulamben, Bali, Indonesia.

Georgette Douwma / Moluccan cardinalfish (Ostorhinchus moluccensis) next to hydroids, brittlestars and sea squirts. Tulamben, Bali, Indonesia.