Exactly what I was thinking...You can see this by it trying to hide behind the sponge filter. Give it something to hide behind, some rocks, fake plants something till it gets some size and reaches maturity and won't be so inclined to hide so much.
When I try to place a mirror on side of the tank it just gets shy and moved to another end of the aquarium.By the way what is that 10 % then?i would say 90% SRD nice looking little guy give him some time in no time you will be asking us for help on how to make him stop attacking you when your hands are in the tank.
If your going to keep in him that bare bottom tank put a small mirror on the side of his tank for 15-20 minutes a day keep his colors and helps his KOK