A live well oxygen and temperature level alert and control apparatus including a temperature sensor and oxygen sensor con figured to sense the temperature and oxygen level of a live well. The sensed signal is seat to a controlling and monitoring apparatus. The controlling and monitoring apparatus is linked to a heating or cooling control system of the live well. Further, the alert apparatus may be configured to control the supply of the fresh or salt replacement water to the live well by controlling a valve supplying such water. The controlling and monitoring apparatus is configured to alert a user about the oxygen and temperature level of the water inside the live-well and control these levels via a user interface. The further inventive aspects can be embodied in one or more of a display screen, a speaker, and an alarm for communicating oxygen and temperature level to a user.