There is a good R&LHS issue on fish cars, FYI.
Most cars were owned by their states' DNR, and used to restock streams along the line with bass, northern, and trout. They would normally park ontop a bridge, and throw the fish off.
One such car, named the Badger II, survives in Wisconsin. The wherabouts of Badger I is unknown, after it left for Canada in the 20's.
http://www.midcontinent.org/collectn/woodpas/wfc2f.jpg
There's a pic of the car at a Fish Fry in Antigo, WI when it was still used as a fish car (yum!!)
They are going to restore it if they can match the funds needed for the restoration.
The J. G. Shedd Aquarium in Chicago had it's own car, named the Nautilus, that they would send to the oceans, and bring back fish, sharks, small whales, etc. The car still survives at the Monticello Railway Museum...
Phil