sick fish??

[Kephren01]

I have a snow white albino... yesterday he looked fine. today he has a little red spot on him... I didn't know if it was a little love bite from one of the other fish or if it is actually a problem. I had some Melafix so I thought id put it in tonight to treat for "red sores" with the thought that if there is a problem, id go buy some meds and keep putting it in... and if its nothing... then i'll just not put any more in. see attached pics...
what do you think? :-\

 

[Kephren01]

My filter system, the intake sits maybe 2 inches from the bottom of the tank, could that be causeing a problem? could it be that fish are getting sick being in that bottom section for a while, then when they get to weak to swim and stay down there it just finishes them off? Or does the water just circulate freely and no big deal?

I could imagine i'm doing something very trivial wrong... wrong lights, to humid near the tank, i'm not around enough? i've been going at this for months