The Loch Leven Seafood Restaurant is located down the road to Kinlochleven from North Ballachulish near lots of lovely B&Bs. Not only is the food fabulous at Loch Leven but the restaurant has a vast wholesaling business attached that happily retails fish to the public.
When I went there in July, I bought an enormous 6lb lobster that they cooked for me on the spot and loaded me up with soft clams, razor clams (very under-rated), languostine, scallops, kippers, sole and white-fish fillets. Not only were they incredibly lovely people, but they vacuum packed our fish, threw in lemons and some home-made mayonnaise and charged me a very reasonable price for it all!
You could even take your gorgeous fresh fish back to your B&B and have it cooked at home to perfection! If you go late in the afternoon you may even be given some of the fish that has been unsold from the restaurant that day. I could not recommend The Loch Leven Seafood Restaurant highly enough.