In carp during 1st year the course of dynamics of the 3 known stages of Sphaerospora renicola showed an increase of the kidney infection in winter and spring (with inhibited sporulation). The winter/spring-peak was accompanied by an intensive blood-phase (C-stages). After August of the 1st summer the swimbladder-phase (K-stages) was not observed, although SBI occurred between January and April. Under warm water condition this infection was discharged after September/October, the SBI never occurred after this time. In contrast to the 1st summer, affected kidneys were often found during winter and spring. In the period of the second outbreak of SBI, C-stages often occurred in the capillaries of swimbladder and in the kidney. The declining phases of SBI, observed from August to April, were not connected with the temperature conditions.