Comparing the effects of feeding a grain- or a fish meal-based diet on water quality, waste production, and rainbow trout Oncorhynchus mykiss performance within low exchange water recirculating aquaculture systems

► Rainbow trout growth, feed conversion, and survival were similar between diets. ► TP and true color were greatest in water recirculating systems fed a fish meal diet. ► TAN, TSS and BOD were greatest in recirculating systems fed a grain-based diet. ► The microscreen filter removed more TSS, TP, and TN than the settler for both diets. ► Grain-based diets can be used to produce trout within low exchange systems.