Tuna is a great protein to get in. Most of the canned tuna fish need to be mixed a bit.  

If you can afford some of the better tuna - buy it.  Some of them, like Oregon's Choice, have different flavors added.

To Puree Tuna is fairly easy:

Ingredients:

1 6 ounce can of Tuna

1/3 cup of real Mayonnaise

1 hard boiled egg

Either one lemon or juice from pickles (whichever you prefer)

Ingredients

Open the tuna and pour out the water/oil and the Tuna into a medium size bowl.

Add 1/3 cup of Real Mayo - not the fake stuff. Using a fork mash these together until you have a nice paste.

Add one hard boiled egg and mash it together.

Then add either lemon juice or the juice from a pickle jar -- just a tablespoon - or more to taste

Salt and Pepper to taste.

Remember, eat with a small spoon - take your time.