First observation of predation by the Panamic green moray ( Gymnothorax castaneus ) on Russell's oarfish ( Regalecus russelii )

This study documents the first recorded predation of Regalecus russelii by Gymnothorax castaneus on Santa Catalana Island, Mexico. Observed feeding tactics included grasping, shaking, knotting, rotation and a novel muraenid behaviour: intraphagy, entering through the oral cavity to consume the prey from within. This provides the first evidence of nocturnal and amphibious feeding for G. castaneus, and the behaviour of knotting confirms its role as an opportunistic predator and scavenger, expanding knowledge of both species' trophic ecology.