Development of the Digestive System and Digestive Enzymes in the Marine Ornamental Fish White-Barred Goby Amblygobius...

Analysing the development of a digestive system and enzyme activity is crucial for understanding the digestive physiology of larval fish and determining optimal feeding practices. The white-barred goby (Amblygobius phalaena), a popular marine ornamental fish, has established breeding and larval rearing techniques, but research on its digestive physiology remains limited, which is essential for enhancing commercial production efficiency. This study aimed to elucidate the histological structure of the digestive tract and changes in enzyme activity in white-barred goby larvae to understand the progression of their digestive functions, providing a foundation for future weaning studies. Histological observations revealed that 6-8 h before hatching, the digestive tract appeared as a simple straight tube, with the liver, pancreas and gallbladder already formed. Gastric glands developed by 35 days post-hatch (dph), at which point the larvae reached a total length of 15.70-18.50 mm. The stomach reached full development at 40 dph (20.11-25.12 mm). Analysis of digestive enzyme activity showed that the total activities of trypsin, amylase, lipase and pepsin in white-barred goby larvae gradually increased with growth. Lipase and pepsin specific activities peaked at 40 dph (19.58-25.13 mm). Based on these results, we recommend to introduce artificial feed starting from 35 dph (15.70-18.50 mm). The findings of this study are significant for improving larviculture and establishing the weaning time of white-barred goby larvae.