Found this while Googling for nostalgia.
Aqua Stock was great. Went there a lot when I was a teen in the 70's and 80's.
The store was huge, stretching from the main entrance on Warren Street to the rear on Murray Street. One block away from City Hall Park. They had a good marine section, and lots of tanks with just plants. The right wall was continuous tanks though a big wood unit was past the middle with larger tanks with discus and angels.
They were big enough to have their own store brand -- Aquarium Stock Company. Their prices were moderate to moderately high. The quality of the fish was very good. They had a lot of experienced employees working there who could dole out good advice. No pressure, I remember a lot of patience - especially with a teenager with limited funds.
A man in dress shirt & slacks with dark hair and a mustache used to stand around the middle near the tanks, across from the long counters. He'd call out in a strong voice asking if anybody needed any help.
I think that one of the things that contributed to their demise was the rise of the discount pet store chains with flashy, tiny tanks with several colors of glass gravel and cheaper, immature fish. Petland Discounts, Fishtown USA, etc. Aqua Stock was more old-school, and from pre-all-glass tank era. I'm sure their rent wasn't cheap either.
Thanks for the reference to the Modern Aquarium article. Here's the link to the issue, it starts on page 11.
P.S. several storefronts up Warren St. was the small, cramped original location of B&H Photo, before one of their several moves and expansions to the current location.