1. Faculty of Fisheries and Protection of Waters; South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses; Research Institute of Fish Culture and Hydrobiology; University of South Bohemia in Ceske Budejovice; Vodňany Czech Republic
2. Department of Gamete and Embryo Biology; Institute of Animal Reproduction and Food Research; Polish Academy of Sciences; Olsztyn Poland