A drain fixture with a mechanically coupleable outlet fitting is described. The drain fixture includes a drain body having an aperture in a bottom floor thereof. A coupler with cylindrical body is inserted through the aperture such that the body extends below the floor. An outlet fitting is disposed beneath the floor and receives the body of the coupler therein. The outlet fitting includes a plurality of projections in an interior surface thereof that are received by respective channels in the body of the coupler. The outlet fitting is rotated with respect to the coupler to mechanically join the two together, such as in a bayonet-style coupling. The joining traps the floor of the drain body between flanges of the coupler and the outlet fitting. Downstream tubing can be coupled to the outlet fitting as desired.