I don't know about regulations concerning tanks but I would think a 75g or smaller would not be problem.Your going to pay how much rent? $2700 per month? That's is insane.If it's short term,maybe.If not buy something,anything.Then electric,gas,phone,cable,fish,corals,car,maybe?Shop around,look in brooklyn,maybe an apt. in a 2 family house.These are usually downstairs[first floor] and the homeowner may work with you on the tank issue.Just an idea.