Nanà is a very good little restaurant not far from the Quirinale in Rome. The feature is seafood - which is fresh and delicately handled. I recently had a lunch there on a one day business trip from Florence to Rome and the food was excellent.
I had paccheri with fresh fish and cherry tomatoes, and my friend had zuppa di pesce. Both were outstanding - piping hot, fresh, just cooked, and full of flavor. We had two glasses of wine, desserts (very good), and coffee, as well as a bottle of water, for around €65 including cover and service. Not an economy meal, but a very good one!
Below is the restaurant on Google maps:
Via Della Panetteria, 37
Tel. (39) 06 69 19 07 50