We used to call the smaller oxbows "borrow pits".
Bob, this may be an example of how the meaning of things changes from place to place and time to time. "Borrow pits" was the term used by the Corps of Engineers for the chain of shallow pits on the river side of the levee where the dirt had been removed to build the levee, itself. You are right about the diversity of "trash fish" in them. Actually, we pronounced the name "bar pit," and I would have probably spelled it that way, too, at the time.
Lou
