The main aquatic ecosystems of Hungary is a network of lowland rivers, with morphometry amended in the dominant extent as a result of regulatory work which  led to the creation of many oxbow lakes. The Water Framework Directive requires Member Countries duty to follow recommendations the specified in the methods of water management and evaluation of habitats and water. Therefore, in Hungary there is now an urgent need to develop a "rapid methods" classification of individual oxbow lakes into one of three specified categories, and determine how to further exploitation of the various water regions.

Hármas-Koros River lies between the mouth of the Tisza and the city Békés. In the nineteenth century the last century, the work of regulatory her bed was made, which resulted in 44 oxbow lakes were created, of which 36 still exist today.

In work 14 oxbow lakes was selected and the following objectives were carried out:
1. The classification of oxbow lakes based on selected criteria (the manner and intensity of water exchange, sediment thickness, redox potential, usage, ichtiofouna).
2. The assessment of the state of spawning and its impact on ichtiofauna.
3. Determination the best  methods of water management in particular types of oxbow lakes, which could stop their further degradation.

The obtained results led to the following conclusions:
- Tested oxbow lakes belong to different categories

- Anthropogenic factors had a negative effect on the conditions of fish reproduction and survival of their juvenile stages.
- The management of fisheries was not a factor differentiating the individual water regions, but had an impact on the ecological status.
- For the maintenance and / or improvement of the natural environment of  the individual oxbow lakes significant impact may have fishery management, carried out in the following years.

DOI: https://doi.org/10.3846/enviro.2017.057