The effects of residual salts and free amino acids in mysid meal on growthof juvenile Japanese flounder Paralichthys olivaceus

This experiment was conducted to investigate the effects of residual salts (mainly NaCl) and free amino acids in mysid Archaeomysis vulgaris meal on t he growth of juvenile Japanese flounder Paralichthys olivaceus. Five experi mental diets were designed. Diet 3 contained fish meal as sole protein sour ce. Fish meal was replaced by de-salted mysid meal at the level of 37.5% an d 77.5% in diets 1 and 2 respectively. Diet 4 contained 82.0% mysid meal an d diet 5 was a commercial diet. Fish with mean body weight 0.16 g (experime nt I) and 1.35 g (experiment II) were fed on the above diets for 14 days, r espectively. Both size of juvenile flounder (0.16 and 1.35 g) fed the 77.5% de-salted my sid meal diet showed significantly better (p<0.05) growth than that fed the 82.0% mysid meal diet. These results clearly indicated that the excess amo unt of salts in the diet reduced the growth of juvenile flounder. On the ot her hand, the best growth was shown in the fish fed the 37.5% de-salted mys id meal diet containing 81.4 mg/g free amino acids (FAA.) in total nitrogen compounds. The FAA analyses of fish total nitrogen compounds showed a simi lar profile to 37.5% de-salted mysid meal diet. These results suggested tha t growth of Japanese flounder juvenile was found to be affected by dietary FAA levels in de-salted mysid meal.