Saltwater or Freshwater Fish, Which Is Better for You?
Whether saltwater or freshwater fish is better for you than the other isn't important. It doesn't even matter which of them tastes better.
What's important is which types contain the lowest amounts of mercury. Equally important is which types have the most omega-3 fatty acids, which are important for good health.
We tend to get more omega-6 fatty acids than omega-3 fatty acids from animals other than fish. We can get omega-3 from non-animal sources, but eating fish is the easiest way to get it.
Fish and Rice Diets
People eat more fish and rice in the Asian countries, like Japan and the Philippines, than anywhere else. Filipinos consider themselves poor if that's all they can eat. They don't know how wrong they are.
Many varieties, along with shellfish, contain important omega-3 fatty acids which add to overall health more than other types of meat (like beef, pork, etc.). People who have regular servings in their diet tend to live longer than those who don't.
I add fish to my diet when possible, and I've managed to eat tuna a few times a month (usually in a tuna salad sandwich or a torta), which is what authorities recommend as a limit due to the levels of mercury found in most tuna. I disagree with the authorities because tuna has selenium as well, which counteracts mercury.
Fish With the Lowest Levels of Mercury
According to the US FDA chart of Mercury Levels in Commercial Fish and Shellfish, some fish I've seen being eaten the most in the Philippines are on the list as having the lowest amount of mercury.
The fish (and shellfish and whatever) that I've seen eaten are, in no particular order: Clam, shrimp, squid, octopus, mackerel, tilapia, milkfish, sardines and even some tuna (but not very often). The dried fish varieties are also eaten a lot, but I can't remember their names.
I'm not particularly fond of fish. I prefer beef, but I think I need to change my ways. Clams, mussels and oysters are okay if they're cooked. I don't like anything raw. It's been more than several years since I ate sardines, and I need to add them to my diet. I didn't like sardines back then, but our tastes change as we grow older. At one time I couldn't stand corned beef either, but now I like it.
Fish With Omega-3 Fatty Acids
Omega-3 fatty acids benefit the heart of healthy people as well as those at high risk of (or already have) cardiovascular disease. Coincidentally, most of the fish that have the lowest mercury levels have the most omega-3 fatty acids. I wonder if there's a correlation somewhere. Somehow I doubt it because some of those with the highest levels of mercury also have a high level of the acids, like tuna.
Speaking of tuna, the chicken of the sea... In the film feature titled Finding Nemo, Nemo was a clownfish. Anyone who remembers "Charlie the Tuna", the mascot for StarKist, would know that Nemo should have been a tuna. Why? Charlie the Tuna was based on actor-songwriter Henry Nemo. How's that for some totally irrelevant information? I just threw that in there to irritate you.
The gist of all this is simple. Eat more fish and less of every other kind of animal. You'll be better off if you do.