Flee the crowded sidewalks of Belém's epicentre for this modern and excellent seafooder a bit down the road, where stacks of top-notch fish and crustaceans are on display, ready to be transformed into Portugal's well-documented seafood delights. Consider the spider crab served in its shell, the excellent rices (with grouper or lobster) or piles of barnacles, clams etc by the kilo.
It's not cheap, but the modern atmosphere and less-surly-than-average waitstaff combined with excellent dishes eases things considerably.