) is an important commercially cultured fish in China, Japan, andKorea. The rapid development of the Japanese flounder aquaculture has led to problems with various diseases that havereduced growth rates and caused huge economic loss. One way to address these problems is to cultivate strains withcharacteristics such as high growth performance, breeding survival rates, and disease resistance. For this purpose, 38families and a control group were established in 2009. Four to five months after hatching, 33 of the 38 families and thecontrol group were selected for exposure to . The surviving individuals were marked with fluorescent-dye and cultivated in two cement pools. Four hundred days after hatching, lymphocystis disease (LD) broke out inone of the pools containing 16 families and the control group. The average rate of incidence was 62.4%; those families(Families 8, 15, 39, and 104) with disease incidence below 40% were defined as disease-resistant. At the same time, 100fish selected from each family were marked with fluorescent-dye and cultivated in different cement pools. Roughly 580 dafter hatching, breed survival rate (580-BSR) and body weight (580-BW) were determined. For the 38 families, the average580-BSR was 32.0%. There were seven families (Families 5, 8, 27, 75, 90, 119, and 125) with a 580-BSR above55%, and they were defined as high breed survival rate families. Notably, in 6 of the 7 families, at least one parent wasderived from F0750 (Family 50 established in 2007), suggesting that individuals from F0750 may effectively improve580-BSR. Chi-square tests indicated that body weight (400-BW) and total length (400-TL) of the resistant group weresignificantly higher than those of the susceptible group (