p. 143 - 155 UBER DIE AKKLIMATISATIONS VERSUCHE MIT SILBERKARPEN (Hypophthalmichthys molitrix VAL.)UND MARMORKARPFEN (Aristichthys nobilis RICH.) UND DAS VORHABEN ZUR EXTENSIVWIRTSCHAFT MIT SPIEGELKARPFEN (Cyprinus carpio L.)IN BRACKWASSERFUHRENDEN INNEREN SEEGEWASSERN DER DDR B. Schildhauer Institut fur Hochseefischerei und Fischverarbeitung Rostock DDR Abstract Investigations into acclimatization of phytophagic cyprinids in stretches of inshore waters in the GDR were begun in 1973. It could be proved by fish keeping experiments in cages in the stretches of inshore waters Kleines Oderhaff, Peenestrom, Rugenboddenkette, Darsser Boddenkette (Saaler Bodden, Koppelstrom, Bodstedter Bodden) that especially in the inner parts of seawaters (with a relatively low salt content and a high eutrophi- cation deegree) can be considered for the introduction of phytophagic cyprinids. Investigations into food consumption proved that the available phytoplankton is not taken up selectively. A preference for certain species was not discovered. In place with an increased zooplankton amount there was a negligible increase in the corresponding amounts in the food. Marking experi- ments in connection with releasing experiments in coastal waters showed among other findings less growth in fish in brackish water (despite a higher food supply) than in the inland waters of the GDR. The existing temperature diffe- rences (approximately 3 grade C Tw) between coastal and inland waters can be seen as reason for this results. However, the phytophagic cyprinids are an effective alternative for fish farming in the partly hipertrophic inland waters, which will be put into practice in connection with the extension of a warm water rearing production unit in the coastal countryin the 90 ices. At present studies into extensive fish farming of carp in the Saaler Bodden - a 8,500 ha large hipertrophic oligohalinic inland seawater - are being prepared. Orientating preliminary experiments with marked young carps are to provide basis data concerning the migration behaviour, growth results, catch, and the viability of this system of fish farming. Those questions connected with the practise of the experiments and the process of extensive fish farming are under discussion.