Page "Ancistrus" Paragraph 10

Males of these species are competitive and territorial.

Males display to each other by positioning themselves parallel to each other, head to tail, with dorsal and caudal fins erect and cheek odontode spines everted.

If this escalates to combat, the males will circle each other and direct attacks at the head.

If an intruding male manages to evict another male from the nest, it may cannibalize the other male's young.