Colour fading on my sucker fish

Question
I have a 30 gallon fish tank with a whisper 30-60 filter which contains community fish and 1 larger (approx. 6 inch) sucker fish.  Normally his colors are a nice dark brown with his usual spots but i just recently made a big move and therefore had to drain  all the water from the tank and keep my poor fishies in a bucket for 2 days until I was able to get the tank set up for them.  Once I had them back in the tank with the new water I followed all the appropriate steps that are required when setting up a new tank.  Everything was fine and all the color came back on all the fish including the sucker fish.  The water is beautifully clear but in the last day or two I noticed his color fading particularly on his belly and between his eyes as well as in smaller patches on other parts of his body.  He's not moving around as much as usual either.  All the other fish in the tank are fine, vibrant and lively.  I have also put the fishtank in front of the window since I didn't have too many options in my 1 bedroom condo.  I also didn't put the poster on the back of the tank to keep out the sunlight until today when I noticed he hides behind the filter when the sun shines in the window in the morning for a short period.  But the other fish seemed to really enjoy the sunlight so that's why I left it off.  In my old place he had a bit of a darker environment.  I'm begining to suspect he just needs more darkness.  Am I way off on this?  If you have any suggestions or tips on why my poor baby is not feeling well I would appreciate it.

Thanks

Kat

Answer
Hi Kat,
 You are probably right that he wants it darker, or at least a good dark spot he can hide in.  Most suckermouth cats hide during the day and only come out at night so he may be feeling very exposed.

-- Ron
  rcoleman@cichlidresearch.com
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