what killed my new betta

Question
dear chris   I have had this betta for 7 days .At the time I got my betta I also bought a betta kit. IT came with a small tank  and waste adsorbing crystals . I rinse both with tap water and let them air dry. i place distilled  water in tankand let it sit for about 2hrs . then put my fish in .  fish was doing fine . this morning when I gave him his food he had this milky white slim on his skin and his color was very dull.  Did I do something wrong or did i get a sick fish. I sorry that I do not have the ph,ammomia and nitrite levels.  

Answer
Hi Jenelle;

Poor guy. I'm so sorry you lost him. He may have had a bacterial infection, parasite or even a fungus. Here is a link with pictures to help you figure it all out;

http://www.petfish.net/articles/Bettas/bettadisease.php

Don't use distilled water. It isn't healthy for bettas because it is missing important minerals that they need. Use regular tap water with a good water conditioner. Here is more on what bettas need;

http://www.healthybetta.com/Care/page1-general.htm

At Your Service;
Chris Robbins