Colors are part of camaflouge. Perfectly fine. Try placing some pleco wafers or a cucumber/zucchini slice out at night when other fish are sleeping for him to eat. You can sink the veggie by sticking it on a fork.
Ok I appreciate the replies, I will increase the frequency of feeding. I was giving it a pleco wafer every other day , I figured it was getting enough from the tank algae and the uneaten food. Typically how many algae wafer should I be giving it?