It all depends how much you are willing to spend. Generally speaking restaurants/hotels in Doha do not know how to cook fish Mediterranean style, if that's what you're looking for. I was at the Fish Market of the Intercon on Fish BBQ night : complete rip-off, don't go there, you eat cold, dried-up tiny bits of sea food on a stick. I hear about La Mer at the Ritz, but never been there, but expect to pay 500+ for 2 without wine.

I've done all other hotel so called sea food theme nights: they are all sub-standard. You eat overcooked, little bits of fish. The ONLY one that i have returned to, is the Veranda at the Sheraton's Health Club building; will cost you 300+ for two plus wine, good quality/price ratio, singer at 8:00 PM, plus a couple of superb grilled fish dishes that i highly recommend. Bonne appetit.