bahamas beach tommy towel::I recently walked along the beach and found quite a few really nice stones that i would like to put in my cold water fish tank bahamas beach tommy towel

bahamas beach tommy towel::I recently walked along the beach and found quite a few really nice stones that i would like to put in my cold water fish tank.
Can i do this without killing the fish?
If you put a few drops of household vinegar on them suitable ones will not react but if they bubble however slight they are no good.
I use the hard yellow ones that are flint.