The spatial and temporal distribution and nychthemeral variation of fish larvae in six stations (Ivinhema, Patos, Paraná, Cortado, Baía and Guaraná) in the floodplain of the high Paraná river are provided. The paper also provides the relationship of this distribution to some environmental factors. From March 1992 to February 1993 ichthyoplanktonic samples were collected by conic cylindrical nets, with 0.5mm of mesh size and fluxometer attached, in 10-minute hauls at the surface and bottom during nychthemeral cycles. At the same time water samples were taken to determine environmental factors. During the above period 5,672 larvae were collected: 57,6% from Cortado station and 13,2% from Ivinhema and Paraná stations. The greatest densities were recorded between October and February, chiefly at night at the surface and by day at the bottom.
Fish larvae; ecology; distribution; floodplain; Paraná river