Deep-sea fish communities in the Southeastern Pacific Ocean were studied using stable isotopes to understand their food web structure. Different fish species were found to have varying levels of carbon, nitrogen, and sulfur isotopes in their bodies, indicating their diets and habitats. Some fish primarily eat plankton and live in the open ocean, while others feed on small fish and live near the ocean floor. The species Dissostichus eleginoides likely eats prey from the open ocean, while Macrourus holotrachys shows a wide range of diets, possibly due to vertical migrations. This research helps us understand how different fish species interact and survive in the deep sea.