An apparatus for mixing fluids within a conduit and monitoring performance of the mixing is provided. In one embodiment, the apparatus includes a conduit and a fluid mixer coupled to the conduit for mixing fluid flowing through a bore of the conduit. The apparatus also includes multiple sensors for measuring a characteristic of the fluid at different locations in the bore of the conduit downstream from the fluid mixer. A controller of the apparatus can monitor performance of the fluid mixer in mixing the fluid flowing through the bore of the conduit based on the measured characteristic of the fluid at the different locations in the bore of the conduit downstream from the fluid mixer. Additional systems, devices, and methods are also disclosed.