Aspects of the diet of Astyanax janeiroensis (Eigenmann, 1908) (Osteichthyes, Characidae) larvae in the Guaricana Reservoir, Arraial River, Paraná State

Abstract

This study discusses aspects of the diet of Astyanax janeiroensis larvae captured in July 2001, in the Guaricana Reservoir, Arraial River, Paraná State. Samples of larvae were taken at 6:30 p.m. and at 8:30 p.m. The Frequency of Occurrence and Numerical Frequency methods were used for analysis of the diet. Larvae fed on algae, mainly Chroococcales and Chlorococcales, however other items were also registered, as microcrustaceans, others invertebrates and vegetable spores. The digestion degree of the items indicates that those found in the digestive tract of the specimens collected at 6:30 p.m were little digested, suggesting that the species caught the food just near this period, which can be justified by the major capture in that time. Besides that, the limitation in the samplings as in the degree of development of the analyzed larvae, could be influenced the results. The composition of the diet suggests that A. janeiroensis, during its early life history, is an omnivorous species with a high tendency to herbivory, consuming preferably algae.