Reproductive biology

Dragonets appear to be gonochoristic, with no evidence of sex change reported. Males maintain relative large home ranges compared to females and these may be defended territorially during periods of reproduction. Mating systems may consist of pairs or single-male dominated mating groups of two or more females. Some smaller, cryptically colored males may also be in these mating groups and will attempt to court and spawn with females, but will often fail because of aggressive interactions with the dominant male. Courtship and spawning typically commences prior to sunset for most species or possibly just after dawn in some species. A male will approach a female and display his erect fins to her, and, as if carrying her, will ascend with her a short distance into the water column, where pelagic eggs are released and fertilized. These eggs are spherical in the genera Calliurichthys and Re-pomucenus, and in Callionymus from the Atlantic Ocean. The mangrove dragonet (Paradiplogrammus enneactis), and perhaps others in this genus, produces a buoyant egg mass that later breaks up prior to hatching. Spawning may be seasonal, depending upon latitude and water temperature, and may demonstrate one or more peaks during an annual cycle. Serial spawning, with the daily production of eggs during the season, has been suggested for some species. Smaller females of some species with bimodal spawning seasons may defer reproduction until the second season (late summer or autumn).

Next to nothing is known about the reproductive biology of the Draconettidae. Both the spawning mode and eggs are unknown. Owing to their close relationship with the Cal-lionymidae, they are sexual dimorphic, with males being larger than females. They are not likely to be hermaphroditic. Spawning is probably paired and pelagic, with a rapid, short ascent into the water column where eggs and sperm are released.

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