Bidirectional mass selection for body shape in common carp

Bidirectional mass selection for the ratio of height/length (in Cyprinus carpio ) generated a response in both directions. Estimates of realized heritability were 0.47 plus or minus 0.06 and 0.33 plus or minus 0.10 for up and down selection respectively and 0.42 plus or minus 0.03 for the divergence. This means that body shape of common carp can be changed fairly rapidly by mass selection. Presumably, differences in body shape among different genetic groups of common carp are due to different intensities and number of generations of mass selection for this trait practised in the past. The results may be applied to aquaculture by selecting for an increasing ratio of height/length only if high backed fish have some advantage in their own right such as a higher price or improved market acceptance.