The goby Perccottus glehni is one of the most winterhardy species of fresh-water eurythermal fish. Study of grounds of biochemical adaptation of these animals to hibernation under conditions of ice, which are currently absent, are of undoubted interest for understanding of the nature of hypometabolic states. This work deals with a study of changes in the content of glucose and other free sugars in goby blood and muscle tissue under different physiological states: active, prehibernation, and arousal after experimental cooling to negative near-zero temperature. A relatively high glycemia level with fluctuation amplitude from 9.8 ± 2.1 to 24.4 ± 2.4 mmol/ml is revealed. The minimal value of these fluctuations is recorded at the period almost coinciding with the beginning of hibernation, while the maximal value-at the period of artificial termination of the three-month hibernation in ice at −5°C. The high blood glycemia level correlating with that in the muscle tissue might probably be due to a peculiar, probably, protector role of this sugar in adaptive mechanisms of the studied fish, not much due to winter hypothermia, but rather to winter hibernation on ice. The level of disaccharide maltose in muscle tissue that is maximal in April is predominantly in reciprocal dependence on the fructose content that is maximal in July. Dynamics of changes in the mono- and disaccharide content depending on the stage of preparation for hibernation basically coincided with the previously revealed dynamics for the fresh-water mollusc Lymnaea stagnalis, which indicates homology of mechanisms of the low-temperature adaptation for animals of different phylogenetic levels.