RTF & CAPO called it. It is a Platichthys flesus. It'd be nice to get these in the US. Like I said, I caught one about 200 miles up the Garonne River when I lived in Figeac, France. And, kept it alive for years in a 20 breeder tank. It lived on table scraps, crushed land snails, earthworms, and minnows (all I could find for it when I was 12).