ABSTRACT The Chilean clingfish Gobiesox marmoratus Jenyns (Gobiesocidae) is a common carnivorous fish inhabiting the rocky intertidal pools along the Chilean coast. In spite of its wide-ranging distribution, basic knowledge about this species is scarce and as a consequence important aspects of its biology such as dietary composition, dietary selectivity and trophic behaviour have received little attention. The goals of this work were to assess quantitatively the dietary composition of this species, its trophic selectivity, assimilation rate of its prey and to experimentally analysed the role of the prey energy value, pre-digestive and post-digestive limitations in the dietary selection of this species. The diet of this species is mainly based on invertebrates, particularly amphipods, crabs and limpets as the most important food items. In laboratory, crabs and amphipods were the most preferred and consumed items over limpets and snails. Our results show that the amphipod is the prey item that provides to G. marmoratus with greater energy per unit of time of manipulation, which would explain its preference in the laboratory experiments and suggests that G. marmoratus feeds according to the net energy gain of their prey, supporting energy maximization, an underlying assumption of foraging theory.
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