The invention relates to a method for reducing the variation of genetic characteristics of fish progeny in a fish population containing groups varying in relation to the degree of relatedness. The invention also relates to a fish fry and fish progeny produced by this method. In the method of the invention, at least two fish groups (PA, PB) are formed of the fish population (P) so that the average genetic degree of relatedness (r) between the fish groups (RA, RB) is lower than in the fish population (P) on average； such members (RAK x RAN, RNK x RBN) of the fish group (RA, RB) are paired with each other, the average degree of relatedness (r) between which is higher than in the fish population (P) on average to form at least two separate parent generations (PA, PB), and members (PAN x PBK, PAK x PBN) of at least two separate parent generations (PA, PB) are cross-paired to form fish progeny (F1).
