Actavia 0 Lojkásek, B. Lusk, S. Hala, K. Lusková, V. 2004 2004-3-31 121-130 The Odra River, 55.2 kmof its length, is winding through the Poodří Protected Landscape Area, which has total area of 81,5 km². More than 80% of its stream has retained the natural character of its riverbed and the hydrological regime with regular floods. Ichthyologic research was carried out in the period 1997-2001. It took place in 7 localities comprising 3 localities situated in main tributaries and 4 localities of former river arms. Gill nets and electrofishing were used for the research on limnetic biotopes. A total of 22 fish species in the streams (Odra, Lubina, Ondřejnice, and Bílovka Rivers) and 4 other species in stagnant water bodies were found. Out of all identified species, Oncorhynchus mykiss, Pseudorasbora parva, and Carassius auratus are not native species. Anglers identified further 7 species in their catches. The studied river sections are inhabited by the Barbus - Chondrostoma fish community. The highest biomass belongs to the most frequent species Leuciscus cephalus, Rutilus rutilus, and Barbus barbus. Total abundance in the individual localities ranged from 2 416 to 20 392 fishes/ha and total biomass was in the range from 174 to 788.8 kg/ha. The species diversity index H' of ichthyocenoses fluctuated between 2.238 to 3.108 in the area. There were 4-8 species in low numbers in 4 searched pools. The biomass was also low and the diversity index H' ranged from 1.390 to 1.737. 3 49