Journal of Fish Biology (2018) doi:10.1111/jfb.13612, available online at wileyonlinelibrary.com Ultrastructure aspects of Brycon gouldingi (Teleostei, Characidae) related to swimming ability and feeding during larval development F. Faustino*†‡¶, L. C. Makino§, E. Neumann‖ and L. S. O. Nakaghi*† *Centro de Aquicultura da Universidade Estadual Paulista (CAUNESP), Jaboticabal, São Paulo, Brazil, †Laboratório de Histologia e Embriologia do Departamento de Morfologia e Fisiologia Animal, Faculdade de Ciências Agrárias e Veterinárias, Universidade Estadual Paulista – UNESP, Jaboticabal, São Paulo, Brazil, §Campus Experimental de Registro, Universidade Estadual Paulista – UNESP, Registro, São Paulo, Brazil and ‖Piscicultura Buriti, Nova Mutum, Mato Grosso, Brazil (Received 12 April 2017, Accepted 1 March 2018) The larval ultrastructure of Brycon gouldingi related to swimming and feeding from hatching to total yolk absorption is described from scanning electron micrographs. Newly hatched larvae (time zero) had no mouth opening, undefned optic vesicles, an olfactory plate visible as a shallow depression, rudimentary gill arches, neural groove, embryonic fn and a primary neuromast in the dorsal region of the head. At the time of yolk absorption, 55 h post hatching, the larvae presented an optic vesicle comprising an optic cup and crystalline lens; a mouth with tongue, tapered teeth and taste buds; a ciliated olfactory cavity; branched gill arches; flled neural groove signalling central nervous system development; caudal, pectoral, dorsal and anal fns; and neuromasts distributed throughout the head and body. These characters are related to prey capture and swimming ability, key aspects of survival during the larval stage. The results of this study provide important information for exploitation and aquaculture of B. gouldingi. © 2018 The Fisheries Society of the British Isles Key words: B. gouldingi; food capture; scanning electron microscopy; sensory structures; swimming performance. INTRODUCTION The piabanha Brycon gouldingi Lima, 2004 is a fsh species endemic to the Tocantins–Araguaia Basin where it inhabits benthopelagic environments and con- sumes a diet of fruits and insects (Lima, 2004). Between 2009 and 2014 the Chico Mendes Institute for Biodiversity Conservation (ICMBio, 2016) led the IUCN Red List assessment of Brazilian fauna and determined that B. gouldingi should be listed as Endangered (EN). Albrecht et al. (2009) assessed demographic and biological responses to impoundment by the Serra da Mesa hydroelectric dam in the upper ‡Author to whom correspondence should be addressed. Tel.: +55 16 3209 2654 (r.232); email: francine.unesp@gmail.com ¶Present address: Laboratório de Biodiversidade Molecular e Conservação, Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, São Paulo, Brasil 1 © 2018 The Fisheries Society of the British Isles