Climate changes cause changes in species composition in both aquatic and terrestrial ecosystems. For establishment of new species in a fish community, dispersal barriers and competition between species acts as a filter.

The Aim of this study was to detect changes in the fish community in a shallow lake, by comparing the results from test-fishing in the lake 40 years after previous test-fishing. Special interest was directed towards the possible establishment of bream or carp. A decline of the low oxygen tolerant species crucian carp and tench was expected, due to the warmer climate and fewer events of winter hypoxia. The fish community in the lake was compared to six other similar shallow lakes in southern Sweden.