Stress reaction in freshwater fish in response to extreme impacts and during the reproduction period

The original and published data on the physiological and biochemical reactions in fish in response to stress impact and during the reproduction period are presented.It is shown that at the initial period of stress and before spawning the protective functions in fish are enhanced which relates to the adaptation syndrome.However,during the initial period of stress the damaging effects prevail over the adaptive processes resulting in the decrease in the level of resistance(“alarm reaction”according to Selye).In contrary,during pre-spawning period protective systems dominate along with enhancement of general adaptation syndromes.This facilitates the increase in the level of resistance in the parental fish(“resistance stage”according to Selye).Before the spawning the alarm stage is not manifested.The state comparable to strong stress occurs in the parental fish only during the spawning.This state is accompanied by decrease in the resistance of organism in spawner evidencing exhaustion of protective functions(“exhaustion stage”according to Selye).With time,both at stress and after spawning,within two to three weeks period,the physiological-biochemical parameters recover and stabilize with the normal limits.