Don't know if you're still reading this, but if your accommodations have self-catering, I would recommend the little fish markets in Chinatown. You will find kinds of fish there that no restaurant ever has; only catch is, you have to cook it yourself (and in the case of Chinese catfish, kill it yourself, too).

The Moana Surfrider's Hotel Restaurant is very nice. Also, there's an authentic Sushi restaurant within walking distance.

Dukes is the best place for fish!

Jon Dominis is excellent for seafood. Very nice ambience. Or did you want sushi?

we ate in the Red Lobster, it's just in the beginning of Waikiki. It was good and the portion are big.

I'm doubting you are looking for a mainland chain restaurant with frozen food. There is a place right on the beach of waikiki where you grill your own fresh with their sauces---The Shorebird

theres bubba gump shrimp on the top of the mall in waikiki that was a yummy place