Clearheaded:
Hashem does not require us to use ultraviolet light, just to abstain from worms which entered fish from outside. If worms are intrisically visible, but are difficult to see because they are similar in color to the flesh of the fish, they are assur if we know they are present. So if you can’t see them to remove them, you can choose to eat something else, or to remove them using ultraviolet light.
There was never such a minhag in Klal Yisroel, to eat worms which entered fish from outside.
I don’t think any gedolim ate treife fish, although I don’t know about the worms. I did hear that when someone asked how R’ Moshe could have drank water with bugs in it, R’ Dovid’s response was, “If he knew there were bugs in it, he wouldn’t have drank it!”. We can try to figure out how Hashem prevented gedolim from eating ma’acholos assuros which they were unaware of, but you can’t pasken shailos based on that. This issue was brought up by the asifoh, and Rav Karp responded with ra’ayos to this yesod.
I hope my answers were clear.