a lot of african cichlids look like saltwater fish. i remember walking into an LFS that had a tanganyikan display tank and there was a customer explaining to his daughter that it was a saltwater tank (if only he knew)
Africans, some of the more exotic knife fish and certain fresh water rays. I feel that for color you want african cichlids for shape look to asian and south america. I mean sturgeon always had a saltwater look to me with their scales.