yeah you shud always use the addative when cleaning/indtroducing new fish, or jsut setting a new tank up, it removes the chlorines and ammiona from the tap water, its also a good idea to test your water straight from the tap, there alot of things can can go wrong, with me keeping discus at 100 quid a fish its a bit diff but the principles are the same, but every1 dus things different, it does annoy me tho wen i go to a shop n hear wrong advice. fish will live in alot of situations, but does this mean that the fish is happy not neceserily, fish are spose to flourish, not just get by surviving.