An advantage of recirculating aquaculture systems (RAS) is the ability to improve fish and shellfish health and increase yields by exerting tight control over the water quality in the RAS. While aquaculture tank systems can make it easier to monitor and control water temperature, dissolved oxygen, pH and other parameters, first those parameters must be measured. In-Situ handheld DO and multiparameter instruments with Bluetooth connectivity for easy data access and automatic DO monitoring solutions for online operation provide near real-time data for optimum environmental control.