The October 1999 issue of The Nautiloid (newsletter of the North Alabama
Shell Club) carries a brief article on "Shellfish from Fish", based on
earlier work by Harry G. Lee and E. G. Lechman. (The article is anonymous;
Glen Deuel, is that you?) Some marine fish eat mollusks, and gem-quality
shells can be obtained from their stomachs. Is there an analogous process
in fresh water?

Of course, muskrats are well known for carrying mussels out of streams and
lakes to eat them, leaving little piles of cleaned valves. Fishermen
sometimes do the same, to use the meats as bait. Some birds eat snails and
clams, but so far as I know, the shells are not of gem quality by the time
the bird is done with them.

But I don't know of any freshwater fish that eat river mussels or snails.
Are we missing an opportunity?

Andrew K. Rindsberg
Geological Survey of Alabama