I have just started cycling my new ten gallon tank. I have a pearl danio (I lost two this morning) and eight juvenile guppies. I was wondering how I should go about water changes, my pet store wasn't of much help. :: ??? Should I take the fish out first? Can I just put in tap water? How often should I change the water? I have a filtration system in place that seems to be doing well. Also, my one danio (I plan on getting two more very soon) seems extremely aggressive (darting at my guppies) and whenever I even get near the tank he freaks out and darts about and jumps at the water surface to the point where I was forced to cover the tank. Is this normal?