HYBRID VIGOUR AND THE INHERITANCE OF SCALE-COVERING AND BODY COLORATION IN CROSS-BREEDINGS BETWEEN CERTAIN VARIETIES OF THE CARP

Three varieties of carp were chosen as parental stocks for cross breedings:mirrorcarp of the scatter-scaled type （MCS）,fully scaled red carp （RC）,and the Long-chow mirror carp （LMC）.Hybrid offspring （F1） were reared in coexistence withthe inbred offspring at the same stocking rate and in the same pond.By the end ofthe first growing season the average individual weight of the offspring of MCS♂×RC♀ was 50—60% heavier than the inbred RC,and that of MCS♂×LMC♀ was57% heavier than the inbred LMC,meanwhile the survival rate of both hybrids wereas high as the inbred ones.Regarding the inheritance of scale-covering and body coloration,the resultsof our experiment indicate that the scattered scale-covering,and the red coloration aswell,is a recessive character.The second generation （F2） derived from the self-crossof the hybrid （F1） of MCS♂×RC♀ should,theoretically,have 8 genotypes and 4phenotypes.The occurrence of the 4 phenotypes have actually been realized,amongwhich the red mirror carp （scatter-scaled,red coloration） has been a new recombina-tion,distinct from F1 hybrid and from either parent in external appearance.Thescalation pattern and the body coloration of the red mirror carp seem to be theresult of homozygosis of the two recessive genes.Rearing experiment shows that thered mirror carp has a growth rate superior to MCS or RC.It is to be expected thatit should be relatively stable in inheritance and would emerge,as a new,economicvariety of the carp.