How long have you had them? Usually, they get used to the lighting after a while. I have a couple of I.D. sharks they freak out when the lights turn on but then they get accustom to it.
I had them for 4 months now, what do you feed them??? the tank is in a traffic area, I going to get a 125 tank and put in a quiet area, this may make a change. How long have you had yours for, and how fast do they grow??
The ones I have now are only 3". I feed them tiny pellets,bloodworms,brine shrimp,flakes and guppies.
I had a pair that went from 4" to 12" w/in a year then gave them to lfs. When the lights go on, one used to play dead by not moving next to a driftwood while the other darted everywhere.