Feeding of holoshesthes Heterodon eigenmann (Teleostei, Cheirodontinae) of the cajuru reservoir (Minas Gerais, Brazil), in relation to the vegetal biomass on its depletion zone

Abstract

Stomach contents of Holoshesthes heterodon Eigenmann, 1915 (Teleostei, Cheirodontinae), collected in the depletion zone of Cajuru reservoir when it was at its maximum water level in two stations with different vegetal densities, were studied in order to investigate the influence of the flooded vegetal biomass on the food quantity and quality ingested by fish. Eighteen individuals from each station were examined. The standard length was l.53±0.05 cm and l.52±0.05 cm, respectively at the lower biomass (8.19 kg diy weight/ha) and higher biomass (38.10 kg diy weight/ha) sampling stations. The stomach repletion Index (SRI) was applied for the quantitative analysis. The alimentary index (IAi) was used for the quali-quantitative analysis, with the volume of the items obtained through the points method. SRI did not show values significatively different between the two stations, p>0.05, by applying the Mann-Whitney test. In both situations, Cladocera was the most important item. There were no correlation between the flooded vegetal biomass in the depletion zone and the intake of food by H. heterodon. However, as there were no empty stomachs, possibly even the lower vegetal biomass was enough to provide abundant feeding resources.