Vintage Chinese Export Sterling Gilt And Enamel Articulating Fish Necklace A2617

Vintage Chinese Export Sterling Gilt And Enamel Articulating Fish Necklace (A2617) Honestly, I am not sure what this is supposed to be. The fish is sterling, no mark, but tested; the chain is not and is newer to the piece. All the scales are enameled, and there is some enamel loss here and there. It's a bit tarnished. At the moment, if you pull on the wire, the mouth opens. Look at the last two photos. I'm not sure if it's meant to do that, but it looks like there may be a very tiny piece missing once it opens. You can see a very small hole on the bead that might have been attached to the body. It is really a unique older piece; the chain is 22" and is plated, and the pendant is 2.5" by 2". Thanks for looking.