A fluid mixer for mixing two fluid streams 40, 42 includes a set of main lobes 26 defining alternating primary and secondary main chutes 30, 32, one or more auxiliary lobes 28 intermediate two of the main lobes, and an auxiliary fluid capture duct 62. The auxiliary lobes are defined, at least in part, by the discharge end of the duct. In operation, the duct conveys secondary fluid to secondary chutes 36 defined by the lobes thereby improving the performance of the mixer despite the presence of an obstruction 18 that would otherwise impede thorough mixing of two fluid streams.