Malawi Peacocks

Question
QUESTION: Hi,

I bought 8 peacocks for my tank through an online breeder.  After about a week, I found one fish upside down not moving.  I'm wondering what the cause is for just one fish to die?  Stress or water condition?  I'm just worried more fish are going to die now?

I guess I'm also asking what tests should I do with my water?  I currently have a PH tester which seems to pass b/c where I live, the water is high on PH as it is.

I guess I also have one more question now that I think about it.  How often should I change the water.  I've been told once or twice a week to change just some of the water and about once a month to actually vacuum some of the gravel.  Is this the best method?
ANSWER: Hi Steven,
It is hard to say why one fish dies unless we know all the water numbers. You need a test kit to test for ammonia, nitrite, nitrate, GH and KH.(water hardness).
Peacocks are fine with high PH. 8.2 is ideal.
Ammonia is always zero, of course, and so should be nitrites. NitrAtes can be as high as 30ppm and be safe.
Temp around 80 is ideal. GH and KH should be over 200ppm.
Water changes I would do 50% weekly. Vaccuuming gravel? I don't do mine at all because that is where most of the good bacteria live.
How long has the tank been up?
What size?
What type of filtration?
It could have been stress, or your water may be off so get a good tester soon and let me know.

---------- FOLLOW-UP ----------

QUESTION: Thanks for all the information.  My PH seems find and my ammonia and nitrite are both zero.  I don't have tests for the others.  Should I get the water hardness test?  Is there a weekly chemical like "Cycle" that you use to help maintain the water?  I have an AquaClear 110 for my 40 gallon tank.  I got the large filter on purpose.  I've had the tank up for about 4 weeks now.

I believe it's may have been just stress.  Any recommendations on the above questions regarding water care is greatly appreciated!
Thanks

Answer
Hi Steven!
It's always good to have a GH/KH test kit. They are cheap.
This is what I do each week for water maintenance.
I do 50% water changes.
Here is a home recipe I use to replicate the Malawi Lake water.
1 tsp of aquarium salt per 5 gallons
1 tsp of baking soda per 5 gallons
1 tablespoon of epsom salts(for GH/KH per 5 gallons of water.
If you don't use this, I suggest you make a batch based on your tank size. Pre-dissolve please!)
Then each week when you do a water change, replace whatever you take out.
So, if you do a 20 gallon water change, replace 2 tsp's of aquarium salt and baking soda, and 2 tablespoons of epsom salts.
Your fish will love you :-)
Your are probably still experiencing new tank syndrome.
Be patient, it'll clear up with regular water changes and I would also add filter floss to the filter in a seperate filter bag. It really takes out fine perticles.
Any other questions, please ask :-)