This paper aims to establish the energy density and condition factor of two fish species, one iliophagous and another piscivorous, in the upper paraná river floodplain, and possible seasonal and temporal differences. samples were taken from june 2010 to march 2011, and muscle samples were extracted from the region next to the dorsal fin, then rinsed in distilled water, and dried at 60°c. subsequently, they were macerated and burned in a calorimetric pump. regarding the subsystems, the energy density and the condition factor showed significant differences only for prochilodus lineatus (valenciennes, 1837), with higher values at the ivinhema subsystem. in relation to the type of environment, no significant differences were detected for any of the species, for both energy density and condition factor. as for the hydrological cycle, significant differences were found for the energy density and the condition factor of pseudoplatystoma corruscans (spix & agassiz, 1829), with greater values in september and march, respectively. although the analysis for prochilodus lineatus had not evidenced significant differences, we observed higher values of energy density and condition factor in june, pointing out a possible influence of the hydrological cycle on the reproductive period of these fish species. in conclusion, the energy density and condition factor of fish can suffer seasonal and temporal variations, according to the environment and the examined hydrological cycle.
Pseudoplatystoma corruscans; Prochilodus lineatus; energy density; condition factor; floodplain
