too much salmon?
The previous two replies were very good. I suppose you could eat too much salmon.....you could eat too much of about anything.
I doubt however, in the context of what you are asking and your overall diet, that you are going to eat too much of it. A better question and response would include some discussion about the source of the salmon. Not all may agree, but I personally would highly recommend that you ONLY eat wild salmon, particularly wild Alaskan salmon. Also, the flash frozen wild salmon is actually better, in most cases, than fresh salmon. The reason is that it is flash frozen within a few hours of being caught, after being kept on ice. So it is normally more fresh than "fresh".
Farm raised salmon usually has an additive fed to the salmon to turn the meat pink. I do not recommend it. There are other important reasons to not purchase and support farm raised salmon, but I will not go into that here.
I do not know where you live, but if you are close to a Trader Joe's, they have some excellent salmon products. They have wild Alaskan salmon that is very good, as well as a very good canned wild Alaskan salmon. I have been known to open a can and eat the entire contents in one seating, but that's really more than a person needs at once. A half can would be plenty...save the other half for later.
Finally, I would definitely highly recommend salmon over tuna...much less mercury.