Trophically transmitted parasites have complex life cycles that incorporate multiple hosts at different developmental stages. As part of a study quantifying parasite diversity in the Indian River Lagoon, Florida, we documented immature acanthocephalan cystacanths in the mesentery of the frillfin goby, Bathygobius soporator. Sequencing of a 626-base-pair region of the mitochondrial cytochrome c oxidase subunit I gene yielded a 100% match to Southwellina hispida, a generalist parasite with a worldwide distribution. As a paratenic host for S. hispida, frillfin gobies bridge the trophic gap between first-intermediate (crustaceans) and definitive hosts (piscivorous birds). Frillfin gobies in our system consume a variety of potentially infected prey; however, crustaceans accounted for 87% of all identifiable stomach contents. In turn, gobies are likely preyed upon by multiple species of migratory piscivorous wading birds, which S. hispida uses to complete its life cycle. This is the second confirmed record of a member of the Gobiidae serving as a paratenic host for S. hispida. Our study adds to the limited but expanding knowledge of metazoan parasite diversity in B. soporator.