Sick julii cory?

I'm not really sure what is going on with it. There are four of them in my 55 gal, with 3 peppered cory. One of them is a transluscent type color, and just doesn't look as active. I know that I over feed so I don't think that it is because he isn't getting as much to eat- but I guess that could be it. He doesn't have any spots like ich or fungus, but he definitely doesn't look as fat as the rest.
I'm not sure what to do for him, other than I am going to drop more algae wafers than I would normally, but he doesn't seem to have much interest in the food. He just doesn't look good!!!

My tank is cycling, but everyone else is doing fine.
Last night it was .25 ammonia, .25 nitrites, and 5 ppm nitrates. PH 7.4

This is after dosing with Bio Spira on Friday evening, so I've been told not to touch water changes yet- let the Bio Spira do its work. ( I was told as long as the ammonia and nitrites stay under 2 ppm that the Bio Spira is in fact working).

But the fact that the rest of the fish (including the other cories) are doing fine worries me... He is the only one looking poor.