Sick Angelfish

Question
I have had my new aquarium set up for about 2 months now.  It has cycled so I put some fish in it to restart the cycling. I bought angelfish about a week ago and some tetras.  Things were going good, but this morning, my favorite angelfish is floating on its side at the top.  It can swim, but I can tell that its sick.  I have heard about the bladder bloating, but dont know if thats it.  My nitrates and nitrites are normal. I just did a partial water change yesterday because the ammonia level checked out harmful.  That was with a quick dip method,,,,my ammonia checker inside the tank says that its fine.  I just checked the ph which is higher than I would like, but just cant seem to get it lowered with chemicals.  Its in the 7.5 to 8.5 range.  The other angels seem to be doing ok, but they seem to be enjoying being in the caves, but they come out to eat.  I have a 36 gal tank with 4 juvenile angels quarter size and 3 buenos aires tetras.  The angel that is sick is alittle larger.  I dont have a sick tank, so I would have to destroy the angel if I take him out,,,,from having fish previosly over the years, I dont see it getting any better.  Please tell me your opinion.  Thanks, Deborah

Answer
Hi Deborah,
Once your tank has cycled, you must add one fish, then wait one week, check your water chemistry, and if it is perfect, do a 25% water change, and add another fish, wait one week, and so on.  If the fish are small such as neons, you may add 3, and wait.  This in the only way to go if you want healthy fish, and a cycled tank.  Ammonia is the number one killer of fish.  Chemicals to bring down the PH should never be used.  They are very harmful to fish, bring down the PH too quickly, and cause death.  The only way to bring it down is to buy driftwood, wash it very well, leave it in a pail of water for a week or so, until the brown tint is gone, and put it in your tank.  Your PH is too high for Angels, and Tetras. They should be in 6.5 - 7.0 PH. Check to see what is making your water alkaline, it could be something in your tank, such as coral or seashells.  If your tap water is alkaline, they I wouldn't recommend Angel fish, or Tetras.  Chemicals make the PH fluctuate which is deadly to fish.  
This is what is happening to your Angel, he does not have a sickness, it is your water that is making him sick.  There is no danger to other fish, except you may lose them all if your water chemistry is off.  Have your water checked at the Pet store to be sure that your reading is right, and check your tap water for the PH level.
Please keep me posted on your water conditions, and if your tap water is alkaline.  Do not worry about your Angel bringing disease to others in the tank.  I am absolutely certain that the chemicals, and ammonia level have caused this, and others will follow if your water chemistry is off.  Like I mentioned above, fluctuating PH can, and will cause death.  Jumping from 7.5 to 8.0 or the reverse, is deadly to fish.
Lynda