A float may be used as a strike indicator for fly fishing and may be attached without hooks, clamps, grommets, rubbery gripping members, or tying of the line/leader. Instead, the float is attached by friction/interference fit onto a line or leader, preferably by sliding the float up the leader to a thicker-diameter portion of the leader to cause a sufficiently tight fit between the leader and an axial bore in the float. The bore may be tapered in diameter, may have a constant diameter, may have a significantly reduced or tapered diameter or another restriction in a portion(s) of the bore, and/or may have an enlarged end opening, for example. A slot may be provided from the outer surface of the float to the bore. The slot may be a straight slot, a Z-shaped slot, or other circuitous slot including curved, non-planar slots. This way, in addition to the friction/interference between the leader and the surface of the axial bore through the float, there is resistance to the leader sliding out through the slot.