Also, FWIW, many of the species of fish mentioned in either Grim's collation or RyanX's SOTT article are bottom-feeders: catfish, drum fish, and croakers (including spot fish); bream carp also live near the bottom. This isn't true for snappers, sardines, or menhaden, but these are all plankton-feeders (only true for some snappers), as are carp. I have no idea if this is a clue, but thought I'd throw it out there just in case.
Added: From Kniall's recent article, gizzard shad fish and mullets are also filter feeders. Not so with ladyfish, though.