Studies on digestive system and assimilation of a flavored diet in ocellate puffer.

The digestive system in the ocellate puffer was histologically and biochemically examined. Also, the effect of scallop extract as a flavor in a diet on performance of the puffer was investigated.The ocellate puffer lacks a stomach, resulting that its expansion sea observed only esophageal epithelium and expansion sac-epithelium and that pepsin-like activity in the digestive tract from the esophagus to the opening portion of bile duct, excluding the expansion sac, maintained an extremely low level.Performance of the puffer fed the flavored diet for 20 days was much better than that fed the unflavored diet. Better protein digestibility was also recognized in the puffer fed the flavored diets. These findings suggest that favorite chemical stimuli caused by the dietary supplementation of the flavor promot digestive and absorptive functions even in the ocellate puffer having no stomach.