I have replied on the other forum which has a list of restaurant recommendations. I remember finding recommendations on this site but that was a while ago.
We've eaten at the Avenida in the Port and that was nice although we ate inside as it was a bit chilly. The restaurant next to it only has outside eating, but the fish there was great! We haven't been to Casa del Mar yet so can't comment.
I think half the fun is trying all the different restaurants out. There is one further around the port at Bolnuevo which does fish dishes, but we had rabbit paella when we went so can't comment on the fish there. I remember someone recommending La Siesta which is also in that area. There is also another one at Isla Plana which has been recommended before.
Perhaps others can comment?
Lynn