For awesome fish tacos, you should check out Sweet Home Waimanalo. Their fish tacos are lightly seared and comes with fresh pineapple salsa and a lime cream sauce. I highly recommend it! They may be a far trek but definitely worth the trip!! Delicious food and smoothies... Acai bowls, peanut butter bellows, tasty brisket sandwiches.. mm mm good!
You might want to do a search of this board. There was a similar thread about 10 mos. ago, with a bunch of recs. It should still be up. Just plug in "fish tacos", when on the main page of this board.
Personally, I've never had any in Hawai`i, but maybe that's because we live close enough to be influenced by Baja.
sadly the best fish taco i have found in Honolulu are at Chili's, yes... the mainland chain. Even worse than that, I haven't had anyone really contradict me. Certainly in Waikiki you won't find one (and I don't recommend any of the so-called "Mexican" restaurants in Waikiki either. If you are down near Ward Avenue, Wahoo has some pretty good fish taco type food as well.