I wonder if health improves much by eating only fish

Tsukiji Fish Market in Tokyo was big and full of fish and other Japanese delicasses, and I have never eaten that mush raw fisk at one time. The funniest/most mysterial experience from there was when we were led in between two selling tables in the narrow street, into a hall that looked like a place we weren´t supposed to be. Than we were led to an elevator where an employee tried pushing an aliminium table out of it, so that the three os us could get in. It led us us some floors, and we came to a a crowded restaurant. I can´t imagine how so many had found this place that I could never imagine was there.