Glandulocaudinae - Courtship

Courtship

Like other ostariophysans, glandulocaudines show a reaction to chemical signals in the water. Many ostariophysans have a fright reaction in response to an alarm substance. In Corynopoma riisei, it has been shown that a sexually mature male's presence actually inhibits the maturation of immature males. In C. riisei, the female is often situated parallel to and somewhat behind the male, which allows for chemical signals released from the male's gill glands to be carried directly to the female.

Glandulocaudines have complex courtship behavior. In C. riisei, the male has paddle-shaped extensions of the operculum which can be extended perpendicular to its body and twitches and flutters due to movements of his body; the female follows and nips at these projections during courtship.

A croaking behavior is recorded in some species of Mimagoniates. This behavior has a part in courtship as well. Courtship involves the male chasing and hovering near the female. As the male hovers, he will quickly swim to the surface and take a gulp of air and return, expelling the gas and making continuous, rhythmic pulses of croaking sounds, interrupted only by the male returning to the surface for more air. The fish also zigzags while hovering by swimming up and down, when the fish intends to resurface but does not. Croaking behavior may have evolved from a behavior called "nipping surface", a feeding behavior that occurs when the fish is searching for food; the fish often will gulp air when doing this. This gulping of air has no respiratory significance.