This paper is about the design, analysis, and installation of an Internet of Things (IoT)-based smart fish farm with a water recycling system installed to prevent the wastage of water. Sensors play a key role in improving the water quality in a smart fish farm with an automatic controlling system. In this aquatic system, the water flow process is regulated by a proportional-integrator-derivative (PID) controller along with water-level ultrasonic, water temperature, dissolved oxygen (DO) concentration, and pH sensors. Sensor data are collected and stored in the lab server as big data. For automatic operation, these sensors send feedback to the PID controller to operate the fish farm within the specified range of operating conditions. To verify the performance of this designed system, field tests were conducted at the Future Creative Technology Research Institute of Busan University of Foreign Studies and at the Jangsucheon Ltd. farm on Ganghwa Island. This system was tested and successfully installed with good results.