Aquaculture is one of the fastest growing industries in the food industry worldwide,providing more than half of the aquatic products for human beings. However,aquaculture is currently facing problems including low degree of mechanization and automation,low production and efficiency,and so on. Therefore,it is urgent to be transformed and upgraded. The underwater robot is a mobile and flexible underwater operation equipment. Compared with traditional underwater operations,it has obvious advantages in terms of operating methods,scope,and adaptability. After being applied to aquaculture monitoring and operations,it is expected to change the existing aquaculture mode,promote the transformation of the aquaculture industry to mechanization,engineering and intelligence,and alleviate the development crisis of the aquaculture industry. Although underwater robots have developed vigorously in recent years,its application in the aquaculture industry is still very limited,and there are still many technical bottlenecks that have not been resolved. This article focuses on the practical application of underwater robots for aquaculture,and analyzes the key technologies covering water quality monitoring,video surveillance and transmission,target recognition and positioning,high-precision underwater guidance,intelligent planning and motion control,and precise operations of underwater vehicle-manipulator systems in detail. The direction of future development is prospected to provide a comprehensive reference for studying and applying underwater robots for aquaculture. 