The present work aims to use Daphnia longispina as a live food for Marsupenaeus japonicus post larva. The survival and growth rates as well as biochemical composition of the post larvae were determined. The results showed that the mixed food (Daphnia + artificial diet) gave the highest survival ratio when fed to the post larvae of M. japonicus, and its survival reached 90 % during the period of 30 days rearing experiments. The results also showed that the mixed food (Daphnia+ artificial diet) gave the best length and weight comparable to the other regimes followed by the artificial diet. By looking into the biochemical composition of post larvae, it was observed that the carbohydrate content in PL fed on Daphnia was 14.7 mg/dl though Daphnia samples had high amount of carbohydrate (24.57 mg/dl). Total protein recorded its highest value in the post larvae fed on Daphnia + artificial diet. The effect of food types on the proximate composition of lipid showed considerable amount of it in the specimens of Daphnia, while this amount was not assembled in PL fed on it. The highest total lipid was recorded with PL fed on mixed food (Daphnia + artificial diet). However, the post larvae fed on artificial diet had only half the amount of lipid compared to the mixed food. The results indicated that although Daphnia was not proved to be used as a lonely food regime but it gives a promising noticeable result when mixed with artificial diet. 

Daphnia longispina, Marsupenaeus japonicus, post larvae, supplementary food.