I might consider substituting sturgeon. Very similar, easier to obtain, feed and care for. They are distant cousins. But paddlefish much prefer moving water with heavy plankton as they are seiners. They just pull out food almost like a shad. Filtering thorugh rakers/gills. Sturgeon going to clean that bottom and can thrive in ponds. Best fish I have ever eaten is smoked sturgeon. Both species are incresingly being farm raised for caviar as the Caspian is being raped.
