Pepsin ontogeny and stomach development in larval cobia

The appearance of stomach pepsin activity in teleosts is one of the last ontogenetic events during the larval stages, and typically marks the completion of the shift from intracellular to extracellular mode of digestion. The present trial describes the morphological and functional ontogeny of cobia's stomach. Larvae were reared in a recirculated system and fed enriched rotifers in green water, followed by enriched Artemia, prior to being weaned on an artificial diet 25 days-post-hatch (dph). The stomach commenced differentiation at 6 dph, and displayed numerous gastric glands by 16 dph (11.1 mm TL). However, pepsin-like activity was not detectable prior to 22 dph (20.8 mm TL, P < 0.05), denoting a lack of functionality until this time point. Maximum pepsin-like activity reached 29.09 ± 1.47 UHb larvae− 1. Together with the observations of others, the results presented herein shed light on the ontogeny of proteolitic digestion in cobia.

► We describe the ontogeny of pepsin-like activity in larval cobia.
► Activity remains undetectable until 22 dph, 20.8 mm TL.
► Pepsin-like activity appears after the formation of gastric glands.
► Knowledge of pepsin ontogeny can assist in refining weaning protocols.