Of course! It would be better to feed fresh raw fish because it's less processed (a lot of canned fish is preserved in salt water/brine and oil, and I think all of it is cooked) and cheaper. However, some dogs (mine included) just won't eat raw fish, so canned is a suitable option. I buy canned mackeral and salmon. They both have bones in them, but that's okay.
I know that you are in the PNW region, so keep in mind that if you purchase wild PNW salmon, you'll want to freeze it for a month before feeding it because of the salmon poisoning issue.
Yes, feed canned mackerel, salmon and sardines, I always run water over the can real good to get out alot of the sodium first. It shouldn't hurt to mix it with a meal of meat and others will mix it with organs and a egg, I personally don't feed tuna to my dogs.
There's a sale on for 5 oz of tuna at 39 cents a can. Normally, I wouldn't think of feeding this either but the sale is too good to resist. It's packed in water. I'll check the sodium content before I purchase though.
Including fish as part of their regular diet has many health benefits, however, I would avoid feeding tuna more than 1 a week as it is high in mercury. Salmon or Jack Mackeral is a much better alternative.