First report of the non-native gulf toadfish Opsanus beta (Goode & Bean, 1880) on the coast of Rio de Janeiro - Brazil.
Biological invasions are considered an extreme risk to biodiversity, resulting in serious ecological and economic problems. Marine species have been introduced mainly through ballast water in estuaries, bays and inland waters, those bodies are historically threatened by intense urbanization making them highly susceptible to invasions. The gulf toadfish, Opsanus beta has been reported as an invasive species that commonly inhabits shallow water bodies, such as coastal bays and estuaries. Its native distribution range from Belize to Palm Beach - Florida (Gulf of Mexico). The first occurrence of O. beta on the Brazilian coast was in Santos estuarine area, Southeastern region, and the second was further south, in the estuarine complex of Paranaguá, Southern region. Here we report the first occurrence of a single O. beta in Rio de Janeiro coast, which was caught in October 2017, using a beach seine in Bica Beach, a polluted sandy beach located in Guanabara Bay - RJ. Considering the similarities among Guanabara Bay and other areas in Brazil, there is a potential for the establishment of O. beta populations in Guanabara Bay in a near future.