Have you had tuna steaks? They are nothing like the canned tuna. I used to marinate chunks of tuna in olive oil, balsalmic vinegar, spicey brown mustard, onion powder, black pepper and a pinch of splenda. Then wrap each chunk in a large fresh basil leaf before putting it on a skewer. Broil until done (very close to broiler in oven) I usually flipped the skewers over half way through. Tilapia is also nice because it's such a light fish. It seems to taste good no matter how it's seasoned.

Jenn