The swimming crab,Portunus trituberculatus,is a commercially important fisheries resource and mariculture species in East Asian countries.Female crab with fully developed ovary is considered as the highly nutritious seafood.Therefore,the decline in natural stock and increase in market demands have driven substantial aquaculture interests for this crab species since 1990's.However,our previous studies have shown pond-reared females generally have poor ovarian development and lower nutrition value compared to wild females,which leads to low percentage of high quality females with fully developed ovaries from pond culture of P.trituberculatus.Fattening with high quality live food,such as trash fish and clam,has proven to be an effective practice for the improvement of crab ovarian development and nutritional composition.Unfortunately,to date,optimal fattening period is unclear for female P.trituberculatus.The present study was conducted to investigate the effects of fattening period on ovarian development and nutritional quality of female swimming crab by fattening culture and biochemical analysis.The results showed that gonadosomatic index(GSI)increased significantly during the 90-day fattening period while the trend of "low-high-low" was found in muscular yield and total edible yield.The highest total edible yield(more than 42%)was in the females fattened for 30-60 days.Fattening period did not affect the proximate composition of muscle,but the highest protein,lipid and carbohydrate contents,together with the lowest moisture contents in ovary and hepatopancreas,were found in the females with 60 days fattening.The cholesterol percentage(%total lipids)in ovary and hepatopancreas decreased significantly during the course of 0-60 days fattening while phospholipids levels of ovary and hepatopancreas increased significantly during 60-90 days fattening.For the different edible parts,hepatopancreas had the highest triacyglycerol levels.As for the fatty acid composition,the increasing trend was found in mono-unsaturated fatty acids(MUFA)for ovary and hepatopancreas while the trend of "high-low-high" was found in poly-unsaturated fatty acids(PUFA)and highly unsaturated fatty acids(HUFA).Muscle contained significant higher percentage of HUFA than ovary and hepatopancreas.Total amino acids(TAA)of ovary increased dramatically during the early period of fattening while the contents of three sweet amino acids gradually increased during the process of 90-day-fattening.Essential amino acid scores(EAAS)of ovary and muscle were greater than 100 for all essential amino acids(EAA)after females fattened for 60-90 days,which indicated no limited amino acid was found in ovary and muscle.For fattening females,EAA/TAA ratios of ovary and muscle were close to or higher than FAO/WHO/UNU recommended values for healthy food.In conclusion,the fattening would not only improve the total edible yield,but also optimize the nutritional values for female P.trituberculatus.Our results suggested the appropriate fattening period was approximately 60 days for pond-reared females post puberty molting.Those results would not only provide valuable information for the future culture and fattening of female P.trituberculatus,but also facilitate the further study on the nutritional regulation of female quality.