The Macrozoobenthos families key provides a basic identification program for freshwater scientists, as it enables the identification of most benthic invertebrates (macrofauna) occurring in European rivers and lakes down to family level. A total of 222 families are covered in the new edition of this programme, one typical representative of each family being documented in numerous high-quality microphotographic images. About 8.300 pictures were produced for the product. Due to the possibility of identification on different systematic levels (e.g. subphylum, class or order level), a total selection of more than 14.000 images is available.