We are dedicating our project to the study of the Durmersheim gravel pit, as it is a major biological feature due to the lack of fish population. In our study, we will look at the aquatic fauna and thereby investigate the effects of missing fish populations. We will use the nearby Epplesee, which has a fish population, as a comparator. This makes it a suitable object of comparison to determine how coexistence with fish affects the amphibians and the macrozoobenthos of a water body. The latter is defined as the bottom-bound invertebrate fauna, including for example snails, mussels, crustaceans and insects. This is an important bioindicator as well as a basis for the occurrence of birds and other higher vertebrates. Exploratory surveys showed evidence of the presence of unusual animals, such as paedomorphic pond newts and the rare mud swimmer beetle Hygrobia hermanni