I've mixed it with mustard to cut out the calories and fat, but i need to spice it up or it tastes kinda bad. A little Tapatio hot sauce and maybe a bit of onion, and i can put quite a bit of it down.
I also think tuna tastes like shit (although i choke it down regardless...).
Lately i've been grinding my oats in a coffee bean grinder, mixing it with a can o' Tuna, and adding enough egg whites (usually about 1/4 cup or so) to make it moist enough to cook on a non-stick pan. I add onions & cayenne or some sort of spices. It's not too bad... Of course i'm so hungry i'll eat anything right now LOL!
try it with dijon mustard and a few Jalapeno's...Not bad...But my favorite though is with wasabe and mayo..It is a japanese sauce type thing...Not sure if it is sold in the states (haven't been there in about 3 years) but it makes any sandwich outstanding imo...Just be careful how much you use..It will make your eyes and nose water and head tingle
Tuna doesn't have to be just from a can. If you can get some tuna steaks, from time to time, you can bake, bbq, broil, poach or steam them. You just have to make sure you don't overcook it or it will have a very dry taste.
As has already been mentioned, tuna has Omega-3 fatty acids which are good. It is also a good source of selenium, niacin, vitamin B12 and magnesium. Fresh tuna will provide a higher nutritional value than the canned variety.
Tuna is also considered 'brain food' but that is probably because of all the dolphins that get caught in the nets.