Creature feature: the male mouth-brooding Banggai cardinalfish

What does “male mouth-brooding” mean exactly? That the male carries the eggs—in his mouth! That’s an interesting characteristic of all cardinalfish.


Banggai cardinalfish, Pterapogon kauderni, belong to the Family Apogonidae (Cardinalfish). They’re named for the area in which they’re native, the waters off the Banggai Islands in central Indonesia, and are currently listed as endangered by the International Union for Conservation of Nature (IUCN).

Now, back to that mouth brooding! Banggai cardinalfish reproduction begins when the female courts the male with a dance. She then releases about 40 eggs—which are all connected by filaments and referred to as a clutch—from her body and into the water, where they are fertilized by the male. Within seconds, he sucks up all the eggs into his mouth!

And in his mouth the eggs remain for about a month. During this incubation period, it’s believed that the male Banggai cardinalfish doesn’t eat. Some scientists think the male may swallow some of the eggs—by accident or design—as a way of getting some nourishment. Banggai cardinalfish in general aren’t very active, which is probably key in the male’s ability to go for such a long period without food.

Once the incubation period is complete, the babies swim out of the male’s mouth—each a tiny replica of an adult Banggai cardinalfish. Out of the average 40 eggs in a clutch, about 20 babies are born.

Come to the Pacific Coral Reef exhibit at the Seattle Aquarium to see Banggai cardinalfish in person!

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