FIG. 1 is a front side view of the LED tube light fixture showing the claimed design; FIG. 2 is a left side view thereof; FIG. 3 is a right side view thereof; FIG. 4 is a top side view thereof; FIG. 5 is a bottom side view thereof; FIG. 6 is a top perspective view thereof; and, FIG. 7 is a bottom perspective view thereof. The broken line disclosure represents unclaimed portions of the LED tube light fixture.