*googled wimplefish* That's a marine fish. NEVER keep that with a freshwater fish like goldfish. So even if they'd do well together on a social basis (lol) the wimplefish needs to live in a marine environment, and like you may figure, a goldfish can't. Even if you'd manage to keep the wimplefish for a while, the goldfish would soon get it killed with all the ammonia it produces. All marine species are incredibly sensitive to changes in water quality, and especially to wastes and nitrates as these things seldom or never change in the sea. So first of all, if you want to keep a wimplefish, you need a big marine tank with corals, protein skimmers and lots of über filtration. You also need to let the tank cycle completely so that no ammonia not nitrite will show on the test readings, and then you have to start with some hardy kinds of marine fish. (Which still are sensitive compared to most freshwater fish)

So in short, no. You can't keep wimplefish with goldfish. They're far, far, far too different when it comes to their environmental needs.

A simple "No".

Maybe, usually saltwater fish are really expensive!!!
Unless the petshop person was trying to sell him goldies to feed to the wimblefish!