Yes this is a man and yes those are real goldfish swimming around in small bottles and yes - that is a Gundam on his head.
He is known as "Kingyo no Ojisan" 金魚おじさん] (the goldfish man) and also as "Boushi no Ojisan 帽子のおじさん] (the hat man).
If you are lucky then you will spot him on the streets of Tokyo - I spotted him in Harajuku.
Japanese Fashion
If you are interested in seeing more Harajuku and Shibuya fashion then lemme know.