Austrias rivers are exposed to a variety of uses and pressures that directly or indirectly affect fish populations and the ecological integrity of running waters. Information on the habitat requirements is necessary to establish or maintain sustainable populations and further, to reach legislative goals. This thesis is aiming to close a knowledge gap on the microhabitat use of the fish species nase, barbel and grayling and their life stages. In addition, advantages and limitations of habitat modelling techniques are explored by comparing data from six medium sized rivers. All rivers are of comparable size and located in the east of Austria. Univariate and multivariate statistical methods were applied to characterize the physical habitat conditions. Six habitat types were defined using variables depth, flow velocity and substrate. Besides the description of habitat characteristics, the aim of this study was to assess habitat preferences of fishes in their life stages (spawning, juvenile, adult) with the use of two multivariate habitat modelling techniques: ‘stepwise logistic regression and ‘CHAID decision tree. This preference was transferred to the investigated rivers to evaluate the potential habitat availability. Most habitat models had explanatory values of over 80% and revealed that at all study sites, suitable habitat is available. A clear preference of single life stages for specific habitat types was displayed. Both cyprinid species spawn at riffles with high flow velocities (80-100cm/s), depths of about 40cm and gravel. Juveniles prefer shallow (<10cm), lentic (<15cm/s) habitats. Adults prefer mainly deep runs (>1m) and pools with indifferent velocities. Graylings tend to prefer deep (40-100cm) areas with moderate flow (<50cm/s). The gained knowledge on habitat use by fish in their life stages may contribute to an integrative river management approach by applying easily interpretable modelling techniques in future studies.