Biologia reprodutiva de três espécies simpátricas de peixes neotropicais: Pimelodus maculatus Lacépède (Siluriformes, Pimelodidae), Leporinus amblyrhynchus Garavello & Britski e Schizodon nasutus Kner (Characiformes, Anostomidae) do recém-formado Reservatório de Miranda, Alto Paraná

The reproductive activity parameters of the teleosts Pimelodus maculatus Lacépède, 1803, Leporinus amblyrhynchus Garavello & Britski, 1987 and Schizodon nasutus Kner, 1859 was evaluated at a newly formed reservoir in the Araguari River, Paraná River basin, Southeast Brazil. The fishes were captured by gill nets bimonthly from November 1997 to November 1998 at three sampling stations. The stages of gonad development were identified macroscopically in the field and then confirmed by histological analysis in the laboratory. The females of all species reached larger standard length than the males. Pimelodus maculatus in reproductive activity were captured only in November, 1997 and January, 1998 whereas L. amblyrhynchus and S. nasutus were in activity throughout the year. The gonadosomatic index reached the peak during the advanced maturation stage in all species, but the hepatosomatic index and coelomic fat index exhibited distinct tendencies. Length at first maturity was 9.5 cm SL for amblyrhynchus females and 17.1 and 13.0 cm SL, respectively, for S. nasutus females and males. L. amblyrhynchus and S. nasutus are partial spawners. The size at first maturity and type of spawning of P. maculatus were not possible to determine in this work