Magnitude of compensatory growth for different cross combinations. There are four gradient compensatory growth levels of the 9 combinations. Of them, Yy had no compensatory growth while the Yj had the biggest compensatory growth. Yj Heilongjiang carp ♂×Jian carp ♀; Yy Heilongjiang carp ♂×Heilongjiang carp ♀; Yh Heilongjiang carp ♂×Huanghe carp ♀; Jh Jian carp ♂×Huanghe carp ♀; Jj Jian carp ♂×Jian carp ♀; Jy Jian carp ♂×Heilongjiang carp ♀; Hh Huanghe carp ♂×Huanghe carp ♀; Hj Huanghe carp ♂×Jian carp ♀; Hy Huanghe carp ♂×Heilongjiang carp ♀.