Acta Scientiarum Maringá, v. 23, n. 4, p. 823-827, 2001 Stages of the embryonic development of the piavuçu Leporinus macrocephalus (Garavello & Britski, 1988) David Reynalte-Tataje 1 *, Evoy Zaniboni-Filho 1 and Betina Muelbert 2 1 Departamento de Aqüicultura, Universidade Federal de Santa Catarina, C.P. 476, 88040-900, Florianópolis, Santa Catarina, Brasil. 2 Piscicultura Panamá. Estrada Geral, s/n –C.P. 3, Bom Retiro, Paulo Lopes, Santa Catarina, Brasil. *Author for correspondence. E-mail: reynalted@hotmail.com ABSTRACT. Understanding the embryogenesis of a species is a useful tool for locating areas for spawning and for the study of growth of the species in their natural environment. This study was conducted at the Panamá Fish Hatchery in Santa Catarina, Brazil, to characterize the embryonic development of the piavuçu Leporinus macrocephalus (Characiformes, Anostomidae). Description was based on the analysis of embryos collected at 10-minute intervals during the first three hours after fertilization, and later at 30-minute intervals until larva hatching. Piavuçu eggs are detached, transparent, small, spherical, with a large perivitelline space. Hatching takes place 11 hours and 30 minutes after fertilization at an average temperature of 28.2°C. Total length and weight of recently hatched larva were 2.39 ± 0.12 mm, and 0.5 ± 0.1mg respectively. Key words: Leporinus macrocephalus, fish, embryonic development. RESUMO. Estadios do desenvolvimento embrionário do piavuçu Leporinus macrocephalus (Garavello & Britski, 1988). O conhecimento da embriogênese de uma espécie é de grande importância, sendo uma ferramenta útil na localização de áreas de desova e no estudo do crescimento da espécie em ambiente natural. O presente estudo foi realizado na Piscicultura Panamá, Estado de Santa Catarina, e teve como objetivo caracterizar o desenvolvimento embrionário do piavuçu, Leporinus macrocephalus (Characiformes, Anostomidae). A descrição foi baseada na análise dos embriões coletados em intervalo de 10 min, durante as primeiras três horas após a fertilização, e posteriormente em intervalos de 30 min até a eclosão da larva. Os ovos do piavuçu se apresentaram livres, transparentes, pequenos, esféricos e com um grande espaço perivitelínico. Depois de 11 h e 30 min da fertilização, a uma temperatura média de 28,2°C, aconteceu a eclosão. O comprimento total das larvas recém eclodidas foi de 2,39 ± 0,12 mm com um peso de 0,5 ± 0,1 mg. Palavras-chave: Leporinus macrocephalus, peixes, desenvolvimento embrionário. Studies on the embryonic development of fishes, based on the monitoring of the evolution of eggs obtained from breeding in captivity, are a useful tool for the morphological and chronological characterization of events. Research in this area is very important to remove obstacles in egg and larvae identification collected from the environment (Snyder, 1981). Moreover, it may elucidate the ecological grouping of fishes, classifying them according to reproductive and ontogenetic characteristics (Sato, 1999). Piavuçu, Leporinus macrocephalus (Characiformes Anostomidae), may be found in the Paraná and Paraguay river basins. It has a short and thick body, with three dark vertically elongated marks. The rear mark is sometimes diffuse and measures 600 mm (Britski et al. 1999). This species is commercially accepted and well know by commercial and sports fishermen and by collectors of ornamental fish. The fish is of excellent quality and when captured gives a good struggle when large. Fingerlings are very attractive. In spite of all these qualities, the piavuçu has been scantily studied, with no record on its embryonic development or on the species’s larvae. There is a current decline in the population of migratory fish owing to the construction of dams and deforestation along the riverbanks of Brazilian watersheds, transforming extensive stretches of rivers into lentic environments (Sato et al. 1996). The development of studies so that embryogenesis and other initial stages of life may be better understood are thus important to determine the distribution of eggs and larvae, the environmental conditions of spawning and growth areas. The embryonic development of the piavuçu L. macrocephalus will be provided in this paper.