This study provides the concise first record and range extension of Rhinosardinia bahiensis (Steindachner, 1879) in the Espírito Santo waters. The recruitment of R. bahiensis in the São Mateus river estuary probably occurs in the upper areas covered by dense macrophyte vegetation during the winter months. Resumo: Extensão de ocorrência de Rhinosardinia bahiensis (Steindachner, 1879) no Atlântico Sul-Ocidental: o papel das águas rasas estuarinas no recrutamento sazonal. O presente estudo fornece o primeiro registro conciso e a extensão da distribuição geográfica de Rhinosardinia bahiensis (Steindachner, 1879) no Espírito Santo. O recrutamento de R. bahiensis no estuário do rio São Mateus provavelmente ocorre no setor superior durante os meses de inverno em áreas cobertas por uma densa vegetação de macrófitas. Palavras-chave: ambiente berçário, estuário, rio São Mateus, Espírito Santo Worldwide, shallow estuarine habitats serve as nurseries for juvenile fish (Beck et al. 2001), including species of the Rhinosardinia genus (Barletta & Barletta-Bergan 2009; Giarrizzo & Krumme 2009). However, R. bahiensis remains poorly understood in freshwater and estuarine habitats in comparison to the congeneric species R. amazonica, which has been recorded in many previous studies (Barletta et al. 2005; Giarrizzo & Krumme 2009; Barletta & Barletta-Bergan 2009). Previous reports have assumed that the species had a southern geographical distribution restricted to the Bahia state in northeastern Brazil (Carpenter 2002). One record of R. bahiensis was reported in 1997 (MZUSP 51758) from Espírito Santo, also in the São Mateus river basin (northern Espírito Santo), but it is comprised of one specimen that was purchased from a fisherman