I don't think this is normal. Not only the tail is turned upward, it also appears almost horizontally set instead of vertically... like in dolphins and whales. Whatever the details are, it looks like a genetic defect or a consequence of some kind of early trauma. This is the first time I see this kind of deformity in any fish. Crooked spine happens right and left in various fishes but the tail turned 90 degrees? That probably almost never happens.
Edit: in the first set of pics, it does not look turned, just curved upward, so maybe that is all it is. It's a common defect, especially among artificially bred fishes. I am not saying this fish is farmed. I'd be surprised a bit if it was. They are not common. Not too rare but far from common.