The male of this new species of fish sports its sex organ on its chin, though it looks nothing like the members on humans and other mammals.
Called the priapium, the sex organ includes two bony attachments, a rod-like structure (toxactinium) and a serrated hook (ctenactinium), used to clasp the female while mating.
These freshly collected male (A) and female (B) specimens of Phallostethus cuulong were found in Vietnam's Mekong Delta.
Not only are the male fish's sex parts at its head, but also its anus.
The female Phallostethus cuulong has a genital opening and an anus under her throat. Fertilization takes place inside the female's body — a rarity among fish. The male's hook is probably designed to clasp onto her to ensure successful fertilization while mating.