Seems like you could have the best of both worlds by making a horizontal barrier above the coast to coast toothless overflow. The horizontal barrier could be just above the surface of the overflowing water ( say, about the typical width of the space between teeth) allowing unobstructed water flow but still doing the work of the teeth in keeping the fish contained. You could cut inverted teeth in the barrier to allow for flow into the overflow should something obstruct the coast to coast flow.
