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Marine ornamental aquaculture often relies on the production of live feeds that are considerably costly to produce, which poses a constraint to the growth of the marine ornamental aquaculture industry. Introducing microdiets during larval development may help reduce the amount of live feeds needed and therefore greatly reduce the cost and labor involved. However, the digestive tract of m arine larvae is rudimentary in early stages , making the digestion and assimilation of microdiets difficult. A 25-day trial was conducted to characterize the digestive tract ontogeny of Halichoeres melanurus , an ornamental wrasse species not yet commercially cultured, to give insight into potential feeding and weaning protocols. Larval H. melanurus were raised on live feeds , including Parvocalanus crassirostris copepods, Brachionus plicatilis rotifers, and Artemia sp. nauplii from 3 to 25 days post-hatch (DPH) . Larvae (n=10 per time point) were sampled 12 times throughout the trial to analyze growth, digestive enzyme activity, and digestive tract development. The activities of lipase and trypsin were quantified using standard microplate assay s. Histology was used to visualize morphological changes in the digestive system at each sampling time point. Trypsin (Figure 1A) and lipase (Figure 1B) activities were detectable from 3 DPH and increased more dramatically after 15 DPH, indicating the maturation of the digestive tract . The digestive tract remained agastric and was characterized by a unique pouch-like organ , named the oesogaster, located posterior to the esophagus and anterior to the intestine. Further studies will be conducted to elucidate the function of the oesogaster, which has been found in other species of wrasse. Overall, t hese data help us better understand the digestive capabilities of H. melanurus throughout development and will guide future feeding and weaning protocols.