Compensatory,or catch-up,growth is a period of unusually fast growth that follows a period of reduced growth resulting from restricted food availability,or some other unfavorable environmental conditions,including low temperatures,hypoxic conditions,density alternation,etc..The compensatory phenomenon has been found in a wide range of aquatic animals including fish.For some fish species,the magnitude and duration of compensatory growth depended on the length of food deprivation.In the wild,fish often suffer starvation because of unstable food supply.And the underlying physiological mechanism for increased growth potential during compensatory growth is still inconsistent and poorly understood.In the present study,the juvenile tongue sole(Cynoglossus semilaevis),an important cultured fish in China,was selected to research the effects of repetitive periods of fasting and satiation feeding on the growth,body composition,metabolism and energy budget.There were five groups:the control fed ad libitum throughout the experiment(C),and other four groups which were subjected to repetitive periods of fasting and satiation feeding(2∶4,4∶8,8∶16 and 12∶24 days for group S2F4,S4F8,S8F16 and S12F24).Feces and uneaten food were collected twice a day by pipetting during the experiment.All samples were measured at the end of the experiment.The specific growth(SGR including SGR_w,in terms of weight,and SGR_e,in terms of energy)in group C were significantly higher than those in other groups(P<0.05).There was no significant difference in body weight between S2F4 and C fish(P>0.05),and both of them were significantly higher than those in other groups.The apparent digestion rate in C fish was significantly lower than those in other three groups(P<0.05).The energy digestion rate in C fish was not significantly different from that in S12F24 fish(P>0.05),but was significantly lower than those in the other three groups(P<0.05).The food conversion efficiency in S4F8 fish was significantly lower than that in S12F24 fish(P<0.05).The feeding rate in C fish was the lowest(P<0.05).The protein content in fish decreased with increasing starvation period.There was no significant difference in protein content between S2F4 and C fish(P>0.05).The oxygen consumption and ammonia excretion were lower in S2F4 fish than those in other groups.The food energy of the control group was the highest(P<0.05).The food energy assimilated to metabolism in S2F4 fish was higher than that in C fish(P<0.05).The data indicated that the juvenile tongue sole of S2F4 showed complete compensatory growth.The complete compensatory growth in juvenile tongue sole could be attributed to hyperphagia and an improved digestion rate.During the repetitive periods of fasting and satiation feeding,the protein content in juvenile tongue sole was significantly affected.The results provided useful evidence to understand the feeding biology of tongue sole,and were conducive to the best management in largescale aquaculture,especially indoor intensive culture.