This is a tool used to scrape the markings from the wooden shipping boxes, which were the most common way of packing goods prior to the invention of corrugated folding cardboard boxes, styrofoam peanuts, bubble pack, and all sorts of modern wonderful shipping products. The owner or user of this tool could scrape the previous shipper's markings off and use the box over. It would be swell to think that Stanley was being environmentally conscious here, but given their fetish for raping the rosewood reserves, that notion of eco-fundamentalism is fantasy. The scraper also can be used to scrape floors or other rough surfaces (you folks in the northern climes, use it as a windshield scraper at your own risk). It has a long, simply turned, maple (or similar hardwood) handle that has a lacquer finish on the earlier examples and a deep red paint on later examples. A japanned forked metal casting is fixed into the handle. At the end of the casting is a carrier for the cutter that can pivot 360 degrees to permit the tool to be pushed or pulled. A captive lever cap, activated by a simple thumb screw, holds the single cutter in place. The sole is slightly convex along the front and leading edges, and is also slightly convex over its width. The cutter is ground and honed with a shallow radius to the cutting edge, permiting the tool to work uneven surfaces; shipping boxes aren't perfectly flat (imagine that), and the convex cutting edge allows the tool to work these surfaces easier. The tool has a relatively wide mouth.
No one has yet written a definitive type study on these critters (don't understand why), but the logos stamped into cutters of these things pretty much follow the chronology of those on the common bench planes. Other than the noted change in the handle's finish, this tool remained unmodified from its birth to its death.
Box scraping is a rugged profession, and this tool doesn't often show signs of physical damage save for a check or two in the handle or a break in the brass ferrule (it's sometimes missing), but cosmetically it often looks like it was used to scrape barnacles off rocks. It certainly isn't a very elegant tool, but it is a useful one if you're into scraping boxes or whatever. I've never used it to scale a fish, but I don't see why it wouldn't tackle that job rather effectively. Be sure to rinse and pat dry after use.