The aim of the present study was to test the hypothesis that predigesting commercial dry diets for fish with hydrochloric acid (HCl) can contribute to the reduction of the incidence of body deformities in a stomachless cyprinid species intensively reared under controlled conditions. Two different dry diets (Carpco Crumble by Coppens International and Aller Futura by Aller Aqua), their respective variants modified with HCl, and frozen larval chironomids (control diet) were fed as sole food sources to juvenile