Behavioral repertoire of Arapaima gigas (Schinz, 1822) reared in captivity and its implication for welfare protocols

Abstract

The well-being of farmed fish has gained considerable attention in the last few decades, and finding suitable indicators of fish welfare is particularly challenging assumed the diversity of species, each with unique biological needs and requirements. Understanding the behavioral patterns of farmed fish species is crucial in developing behavior-based measures to maintain their welfare and production. However, there is limited scientific documentation on the behavioral repertoire of Arapaima gigas, a commercially valuable and widely farmed species in South America. We provide an ethogram of A. gigas when reared in captivity within a recirculating aquaculture system (RAS) indoors. Observations were conducted on a group of adult individuals (one male, two females) kept at the Leibniz Institute of Freshwater Ecology and Inland Fisheries in Berlin, Germany. The ethogram describes five main behavioral categories: locomotion, feeding, social interactions, agonistic interactions, and breathing. Notably, Arapaima displayed a strong preference for resting motionless, often near a gravel bed area provided inside the rearing tank. Agonistic interactions were rare and mostly initiated solely by the male during feeding sessions. During feeding, pellet food was often picked from the ground, while whole fish feed (dead Tilapia) was mostly swallowed immediately from the surface. The male consistently occupied the provided gravel area as its territory, spending most of its time there. With this ethogram, we aim to contribute to the limited behavioral knowledge about A. gigas, especially when in captivity. Our findings offer valuable insights into species-specific welfare evaluations and enhancement measures with potential applications in healthy aquaculture practices.