I eat a lot of canned tuna. I tried the flavored stuff in the packet, and couldn't stand it. I usually buy the 3 oz cans (the little ones that come 3 to a pack) of albacore white tuna. I buy the albacore because I prefer it, and the smell isn't as strong. The smell doesn't bother me, but I do take my lunch to work and the classroom trashcans aren't emptied until 4 hours after lunch. My students would complain very loudly if the room smelled of tuna.
I eat lots of tuna because of the endocrine disorder I have; my body has a lot of trouble processing carbohydrates, particularly those of the refined variety. Tuna is easy for me to take for lunch.
I usually have one of the cans of tuna (anywhere from 80-100 calories), sliced cucumber, celery sticks, some skim or 2% milk cheese (I love cheese, and its also something I can eat; my favorites are the little marinated mozzarella balls, sharp cheddar, smoked gouda or mozzarella, smoked cheddar, and sharp provolone), and some type of fruit... usually berries, because I tolerate those well. Oh, and 4 or 5 triscuit crackers or 1 cup of popcorn.
Sometimes I'll take some of the healthy request or 98% fat-free mushroom soup and mix it with the tuna and some of those fried onion pieces or I'll crunch my triscuits into it. I also have the cucumber and celery on the side, though with this I often melt the cheese in the mixutre (in this case, grated parmasean and romano, or a shredded cheddar). I'll do this for dinner as well.
I also buy and keep frozen already cooked shrimp in the freezer: it thaws by lunch. Then, I take the mozzarella balls, a tiny bit of olive oil, and mix it together. Veggies and fruit again...
My favorite "dinner" fish is tilapia or flounder... that I throw on my ersatz George Forman grill, and its done in 5 mintues. I tend to buy my fish at Trader Joes, because its cheaper and sold in single-serving sizes.
Dinner usually has a salad of romaine, celery and cucumber, and some "light" dressing. I used to only use fat-free dressing, but that has more sugar in it. The light is 1 g or 2 g more, and has less carbs.
Hope this helps!