Helostoma temminckii are popularly known as kissing fish, as they are sometimes found to lock their lips with other members of the species. You may also find them kissing other types of fish, plants, and objects in the tank, while feeding or bullying. Though the lip-locking act of these fish may appear as kissing, it is certainly not a display of love and affection, as in case of humans. It has been suggested that their lip-locking is a sign of fight for dominance. It usually happens in young males, who want to defend their territory or feeding areas. Such aggressive behavior is also seen during breeding season, to attract females.