AbstractThe Patagonian toothfish or Chilean sea bass, Dissostichus eleginoides, is an ecological and commercially important species captured by the Equatorian fleet in the Southeast Pacific Ocean. This study aimed to determine this species' diet composition and feeding habits captured in three geographical zones from Ecuador during 2017 and 2018. The total length and corporal mass were measured during this period, and the sex and sexual maturity states were determined from 328 individuals. A hypoallometric growth was evidenced by the size‐weight relationship in D. eleginoides, with an allometry coefficient b = 2.34, suggesting that it increases in size more than in weight. The stomach content analysis expressed as the Prey Specific Index of Relative Importance (PSIRI) indicated that D. eleginoides mainly feeds on teleost fish (88.2%) and less on cephalopods (9%) and crustaceans (2.8%). Males and females evidenced a similar diet; however, adults consumed more teleost fish than juveniles. The trophic position ⁓ 4 indicates that the Patagonian toothfish is a secondary carnivore predator with a wide geographic and diet variation related to prey availability. This is the first study regarding the trophic ecology of D. eleginoides in Ecuador, as other studies are lacking. Understanding nutrient and energy flows in ecosystems is crucial for effective fishing management with an ecosystemic approach.