Probably because just easier to catch a predatory fish than a land predator

Throw a line in the pond, whatever bites will bite. Clean it and you've got dinner.

Versus with hunting, historically (and even now) if you miss your shot or don't hit a part that immediately takes it down, now you've got an angry wolf/bear/moose bearing down on you. Wolf is also probably too close to dog for most cultures.

Nowadays you can get meat from bear/moose/whatever, but there isn't much of a culinary tradition associated with them. So the only people out for them are the curious or macho types

I have a redneck-y enough background to have eaten some predators. The meat doesn't taste as good. A lot of it is tougher or stringier. I think pigs are omnivores though, but I don't know what they are fed on farms.

I expect it has something to do with muscle and fat composition and the physical requirements of predating on land vs. in water. A followup question would be what about water-based mammal predators like seals and whales? And what about water-based herbivores like beavers? Can't say how it tastes personally.

Maybe because fish predators are still fish? So they still taste like fish. It seems fish-eating birds taste fishy, which is not really a desirable flavor in a bird. Maybe mammal predators are also not as tasty - then also what do you feed a farmed bear or a fox, they need to eat meat... So you'd feed them cows that we could eat ourselves? Or we raise rabbits just for them?

From a practical matter, most fish in the ocean feed on other marine life. herbivorous and omnivorous fish do exist but they are a bit more rare, and it is more common for smaller/juvenile fish. Also even among those that are primarily herbivorous, they usually go after eggs or very small fish which makes them omnivorous.

The most common fish that we eat are those that other fish also eat, like herring, and there aren't a good comparable land based animal in our current diet. It would be a bit like if a primary diet for humans would be wild rodents.

One reason could be that fish like herring schools, but wild rodents don't. It is easier to hunt large quantity of animals if they are located in the same location and bunched up.

Because another land mammal is far more likely to accumulate diseases, parasites, and maybe toxins that are harmful to us than a fish is.

Bear is (or at least can be) delicious. You can get a lot of tasty meals out of a fat berry-fed bear.

I've never had the chance to eat cougar, but I've talked to folks who have, and they say it's their favorite meat - like a light, tender pork.

We're mammal predators too. Mammal herbivores travel in herd and are pretty easy to hunt. They also pose little risk. The answer is the same as to why lions don't have leopards as their main food source.

I assume it's because there aren't enough of them and they're relatively difficult to hunt/farm. Otherwise I'd be happily chowing down on lions and polar bears.

I think part of it is that the larger animal predators tend to be more muscular, so the meat isn't as delicious.