But tell me, what are the odds of a betta getting eaten by an Oscar..in the wild? That's not accurate at all. Feeder goldfish? They get fed to numerous kinds of fish..yet in the wild, some of those fish don't even eat them. Yeah, it is in their natural instinct to kill what they find as food, but if you're gonna feed them a live product that's not in their food chain, then I find that far from what is natural. Mind you, they are not in their habitat when put in a tank. That's a whole different story. The owner FED the fish, the fish ate it. The betta was placed there, it wasn't in the tank to begin with. And if it was, then the story would be different. But then again, that's why people ask and give advice on what fish is compatible with one another. Specifically saying, I'm not worked up on a fish eating another in the wild, but in fish tanks? Then I find that slightly cruel. The owner should be the one responsible enough to feed what is right, and place the right fish in the tank.
A fish that gets eaten by another in tank is far from a fish eating another in their own habitat.