What kind of tank do you have these in?
You said you don't know about the
nitrogen cycle.
I would suggest you go to :
http://www.fishlore.com/NitrogenCycle.htm
Read it well, and if you aren't set up to test your water, you need to get a
API Master
test kit freshwater (liquid) to test your water.
You should NEVER put a fish in an uncycled tank. You also need to have a tank large enough for these fish....a minimum of 55 gallon tank for these beauties....
If you didn't cycle your tank first, your fish are going to start to suffer from
ammonia poisening. You need to be prepared for daily water changes , or find some bio-spira to help speed the cycle.
Good Luck.