Ick is icky!

Well while I was eating my cereal before school, I was watching my my fish swim about. :smile1:
I noticed one of my neons looked a little different and upon closer inspection, I noticed some Ick.
My dad calling me to get in the car had no time to treat the little guys.
So I got home and put them into my quarantine tank and treated it for ick with that aquapets (I think) that has the clown loach on it and is numbered 6. Treated my main tank as well. :wondering:
So after that long read, my question is: What causes ick and how can it be prevented?:idea:

 

It’s normally introduced by new fish you add.
Did you buy fish recently?

 

I quarantined the cories and only added them today . What about the Campcon blood worms. I've heard they can be the cause,any idea?

 

Its not the campcon.