This study is to focus on the marine cage culture industrial problem of fish size, growth, and feeding. This year, grouper is the main target fish species. Firstly, underwater monitoring of the fish organism length and growth will be carried out in the first half of the year. It is our purpose to develop the underwater monitoring technology for the body length of a fish and growth of fish understand the growth and growth status of fish colonies, and develop lightweight modules to reduce the troubles of cage culture frams. There were design and development of portable modules to reduce the on-site operation of the cage culture. In addition, in-situ experiments areas are the indoor aquaculture ponds in the Mariculture Research Center, FRI and the marine cage culture farms in the Checheng township, Pingtung. The field experiment used AI measure the cultured fish length and growth status. The body length and growth of the yellow grouper results show that the body length and weight error rate value of manual measurement compared with AI measurement is 3.83% and 4.46% in the indoor aquaculture pond experiment. And body length and growth of the dragon tiger grouper results show that the body length and weight error rate value is 1.25% and 7.84% in the marine cage culture experiment. The above results show that the result of AI measurement is very close to the result of manual measurement. The project is expected to reduce the cost of aquaculture production, and further achieve accurate feeding management to maintain the optimal fish growth and the cage culture environment.