Deep-sea pelagic fishes are the most abundant vertebrates on Earth, yet their role in the overall economy of these is poorly known. Low latitude oligotrophic regimes, typified by the eastern Gulf of Mexico, constitute most of the world ocean and consequently support the largest global ecosystems. Thus, we have little information on the trophic role of most of Earth's vertebrates. To address this, the diets of an entire midwater fish assemblage (164 species, constituting > 99% of assemblage numbers) were analyzed to assess feeding guilds and predation impact. Zooplanktivory was the dominant feeding mode (80% of prey biomass taken), followed by piscivory. However, the entire fish assemblage predation impact on zooplankton was only 5-10% of daily production. This points to critical limitations in our understanding of how tropical - subtropical regimes, the largest of global ecosystems, function and which taxonomic groups are the most important zooplanktivores. Regarding the latter, the obvious candidate is other zooplankton, including large gelatinous predators.