I find it interesting that your animal protein choices would ever be considered sadly limited when it's so mainstream in the US (at least in the midwest) to eat far fewer.
It's sadly not unusual for many people to eat beef and chicken (and pork, but only if you count bacon, ham, and sausage) almost exclusively during most of the year (holiday turkey being the exception).
Most of the "fresh" fish available in noncoastal states is actually defrosted from frozen, or never-frozen that isn't so fresh anymore. Freezing is often done on the fishing boat, and canning is done pretty quickly too.
From a nutritional and food safety standpoint, canned and frozen seafood is often better than any fish that isn't minutes out of the water.
As for flavor, there's at least as much flavor variation in canned fish as in non-canned.
Canned foods (and organ meats, which is another story) are unfairly stigmatized in the USA because of their associated with poverty - foods you eat because you have to, not because you want to.
Almost ten years ago, my husband and I had to file bankruptcy due to job loss and our out-of-pocket medical expenses (and our medical insurance paid 90% of expenses with no deductible). As a result, for about two years, we had to seek out the cheapest
of the cheapest food sources.
Canned fish was literally a lifesaver. In the local Asian markets I discovered an astonishing array of canned fish, just in the "Smiling Fish" brand alone.
I went through a bit of an obsessive canned-fish diet myself, and not only because I had to, but because flavors were just so amazing, especially for the price.
You can't find many foods that are healthy, cheap, tastey, and ready-to-eat, but canned fish are one of the rarest of exceptions.
I eat more variety now, and haven't been eating nearly as much canned fish as when I first discovered them, but I also haven't been losing any weight lately, either.
I may have burned myself out a little on canned fish, in my quest to try as many as I could find, but I wasn't deprived in flavor, nutrition, or variety.
If you can find an Asian or global market, sardines alone, can be found in an amazing variety of sauces. Some are a bit high in fat and even sugar by proportion, but even the sweet varieties tend to be very filling and satiating, so you (or at least I) end up eating less.
All this canned fish is giving me a craving for Smiling fish sardines or mackerel in green or red curry sauce. I may have a can in the pantry. Otherwise I'll have to make a trip to our nearest Asian grocery (only five blocks away). The store must carry at least three varieties of fish in at least five different styles of southeast asian curry sauces. And that's not counting other types of canned seafood, like fried clams with chilies.
The fried clams with chillies are one of my favorites, and while the fat and sugar content are a bit high compared to other products, the flavor is so intense I usually only eat about 1/3 of a serving at a time.
Geez, now I'm hungry for those too.