I have some notion that this fish may have been the"bird" on an old sewing bird clamp, but I'm not sure. I just find it a sweet little thing, which someone obviously put some effort into, cutting a mouth in the round part, adding a little wooden fin on the end, and painting with a few decorative details. Now the screw serves a little pedestal and it stands up if situated somewhere flat.
3 1/4" tall and long, 1" thick. The wood shows age and stains, but all the better for it I think.