Interactions between species structure ecological communities and regulate the flow of energy and information across ecosystems. In marine environments, fishes engage in a wide variety of behavioral associations ranging from mutualistic symbioses to opportunistic foraging interactions. However, these interactions are typically studied independently, limiting our understanding of how multiple interaction types jointly shape community structure in local and regional scales. Here we compile four decades of observations of interspecific associations between marine fishes in the Southwestern Atlantic Ocean and analyze them using an ecological network framework. Our dataset includes 234 species from 14 taxa participating in twelve types of behavioral interactions, including cleaning symbiosis, nuclear–follower assemblages, mimicry, hitchhiking, ecosystem engineering, and waste feeding. Temporal patterns reveal increasing research activity since the late 1990s, with a strong dominance of cleaning and nuclear–follower interactions. However, after 2012 the number of studies has decreased across time. Our network analyses show that individual interaction layers (i.e., type of interactions) tend to display nested organization, whereas the combined multilayer network exhibits modular structure. These results indicate that marine fishes participate opportunistically across multiple interaction layers while also forming specialized modules associated with ecological roles. Our findings demonstrate that integrating multiple interaction types provides new insights into the organization and functioning of marine communities.