A Rare Mouthbrooder

March 8, 2012 in General Banggai Info, Slideshow

The Banggai Cardinalfish, Pterapogon kauderni, has an extremely rare mode of reproduction, in which the male incubates a mass of eggs through hatching, metamorphosis, and direct development of fully capable fry.

Male Banggai Cardinal with fry ready for release.

In other mouthbrooding fishes, parental care stops at hatching, after which extremely tiny larvae are released to be carried by tides and currents.

The tiny, newly released Banggai Cardinalfish babies go immediately to the bottom, where they seek protection among the spines of sea urchins, in coral thickets, or in close proximity to the stinging tentacles of sea anemones.

This mode of reproduction explains the extremely limited range of the species. With no larval stage, the usual wide dispersal of marine fish larvae over hundreds or thousands of miles simply does not occur.

The Banggai Cardinalfish is commonly said to have low fecundity, as each spawning results in only 12–60 eggs being brooded by the male. Often fewer than 20 fully developed fry are released per batch. The species breeds year-round, usually on a monthly cycle.

This species is the only reef fish reported to be endangered by collection for the aquarium trade, the explanation being its extremely limited natural range of 34 square kilometers (13 square miles) in shallow waters off 27 islands.

Collection pressure could be relieved on wild populations if more aquarists became involved in captive breeding. One goal of the BANGGAI RESCUE Project is to develop better protocols for captive culture in the Banggai Islands, in commercial aquaculture facilities in developed countries, and by amateur “basement breeders.”