ft(end of the)a: The current just beneath the surface is traveling at 30 miles per hour, and the channel is 640 feet deep.“It’s an underwater waterfall,� he says, slapping Gardiner’s shoulder. It’s falling at 40 feet per second. Upstream of the waterfall is an eddy, the water relatively still. This point is likely habitat for the blind cichlid: calm pockets where sheering currents have trapped the fish at great depths. Deep-river specimens, like the one found today, surface only when the river surges and flushes individuals into the harsh environment of the main flow. In terms of Stiassny’s hypothesis, the finding suggests that the Congo’s currents partition habitat from side to side and from top to bottom—just like a mountain range.