Join Date: Feb 2010
Location: Sacramento, California, USA, Earth (I think)
I would be a lot more worried that it had some other contaminant than limestone (which would be the part that fizzes with acid). Contaminants like oil, pesticides, or something similar. Many apartment complexes hire pest-control folks to spray for ant/roach control on a regular basis. Current insecticides are extremely toxic to fish. Some have gardeners that spray for weed control.
Boiling may not destroy organic contaminants. If you are set on using it, I recommend that you try it first on a goldfish tank with some aquatic weed to make sure.