1. 1 Department of Ichthyopathology and Fish Health Protection, National Inland Fisheries Research Institute, Żabieniec , Piaseczno , Poland
2. 2 Department of Microbiology and Clinical Immunology, Faculty of Veterinary Medicine, University of Warmia and Mazury in Olsztyn , Olsztyn , Poland
3. 3 Pond Fishery Department, National Inland Fisheries Research Institute, Żabieniec , Piaseczno , Poland
4. 4 Department of Ichthyology and Biotechnology in Aquaculture, Institute of Animal Sciences, Warsaw University of Life Sciences , Warsaw , Poland