fat round fish silverplated vase, vintage Oxford silver plate

Vintage silver plated fish (a vase? the mouth of the fish is open - seems like it would look odd holding flowers, so perhaps a holder for something else?). He's very round and fat, and measures about 4 1/2" x 5".

The underside of one fin is marked Oxford plate, s.p. lead (silver plated lead?). We haven't been able to find out anything much at all about this piece, I know! If you know anything about this fishy character, please email us, thank you.