Iridescent Shark Concern

Question
My Id isn't all that old to me, i've had it just over 2weeks now, in the past i was helping take care of some larger ones (7-10") but that was years ago. I've been feeding him shrimp pellets but lately he's been ignoring them, and i noticed his loss of colour, he was a nice silver/grey during the day, and a dark blue at night, now he's almost totally white. I'm extremely concerned with this, because its my favourite fish (the previous two i helped with for years, so i like this fish), and the others are all doing fine. Could it be diet, or possibly because i only have 1 ID currently?
We have 2 Bala Sharks, a Pleco, and 2 Mature dalmation Mollys, with a handful of Dalmation and Silver Molly Fry.
If you can help, i'd appreciate it alot.

Answer
Hi Jay

How large is the tank?
And what's the ammonia, nitrite, and nitrate readings?

You're right, they do prefer to be in groups.  But they grow so large(over 2 feet), unless you have a huge tank, or plan to in the near future, I wouldn't recommend buying more.  They're also omnivores, so they should a varied diet.  A good pellet and flake food for the main staple, spirulina flakes, frozen(and thawed) bloodworms, brine shrimp-live or frozen, cut up pieces of shrimp.

I would first check the water quality though.  Ammonia and nitrites should be reading 0 ppm and nitrates under 20 ppm.  And try other foods and see if that helps any.

Let me know if other symptoms show up or he gets worse.

Christy