Selective breeding is the opposite of natural hybridization. It’s pushing plants in a direction WE like, that wouldn’t happen naturally. Corn only exists because people decided it should, that was a decision made 9000 years ago, but they bred for it, emphasizing traits that made it good food, but wound up with something that propagate without us. The only difference between what we do now and they did to make corn is we’ve got killer microscopes and labs to figure out what gene makes this trait happen and push it that way, they just figured cross pollination through trial and error and got lucky.
“Selective breeding is the opposite of natural hybridization.”
No it is not. It is exactly the same thing. Hybridization is how you selectively breed. It is just physical manipulation of something that nature will allow. Nature allows manipulation of pollen swapping and selecting the best of seeds and pollen from the best of plants. Nature will allow grafting of similar species from one to the other. Or interbreeding animals of a different shape, color, or size.
Putting fish DNA in a plant is not going to be allowed naturally anymore than crossing a cat with a dog. Or a duck with a fish. GMO can force those unnatural combinations. If nature will not allow it then it is unnatural.