We compared the effect of different diets in the biochemical composition, levels of lipoperoxidation and survival rates of males and females of Hyalella bonariensis. These crustaceans live in limnetic environments and different kinds of food habits are present in the genus Hyalella. Adult animals were collected in the spring (September) in a stream near to Salto city, Buenos Aires. In the laboratory, the animals were kept submerged in aquariums, separated by sex, under controlled conditions and survive rates were observed. They were fed ad libitum for 45 days with four different diets, and after this period the animals were used for biochemical determinations. Statistical analysis revealed significant differences in the responses to glycogen, proteins, lipids, triglycerides and lipoperoxidation levels in both sexes of these amphipods taken from the natural environment. Animals that received macrophytes associated a ration with high content of proteins (43%) during 45 days presented the major survival rates (males= 86.6% and females= 96.6%). These responses can be revealed that this specie primarily feeding macrophytes associated with deposit feeder, and that this diet is more generalized. This study showed the importance of the proteins in diet of this amphipod, were the females increased the reserves of proteins and triglycerides with different diets probably for reproductive events and male increased the reserves of glycogen and triglycerides for reproductive events and growth.