On the topic of making your own sushi/sashimi, Atlantic Bonito
is absolutely incredible. The meat is sweet and smooth as silk. I've never seen it available in any store or restaurant, but those who live in the North Eastern part of the US, south of Cape Cod can catch these from any rock pile or jetty along the coast from mid August through September. White plugs and jigs work, but the ultimate is catching them on a fly rod. When venturing out in my boat, I always bring along a sharp fillet knife and some ginger soy. I've made lunch on the spot with quite a few species: striped bass, goosefish, herring, cod, flounder, bluefish (yuck), bluefin tuna, black sea bass, scup, sculpin, sand lances, sea robins, tautog, false albacore (double yuck!), and an occasional sand worm (not as bad as you'd think). jwest
reminded me that Spanish Mackrel is also very good, though difficult to catch with all those teeth.
warning: those from the south often call bluefish bonito. Bluefish taste like crap no matter how you prepare it. Accept no substitutes.