Martin Bláha spent almost 8 weeks in the laboratory of Ecology, evolution and symbiosis at the University of Poitiers, France. I worked with Frederic Grandjean, the expert in the field of population genetics of crayfish and genetics and ecology of crayfish plaque pathogen Aphanomyces astaci. During my stay I finished population genetic analyses of 9 Tyrolean (Austria) populations of noble crayfish and improve my skills working with ABI sequencer. Furthermore, we suggested interesting topics for further research and cooperation with our laboratory of ecology and ethology of fish and crayfish. This stay was allowed due to financial support from Postdok II project (CZ.1.07/2.3.00/30.0049).