try feeding lots of market shrimps and the occasional crayfish...i heard from some experts of the red tailed catfish had fed theirs with highly protein foods..they say that any crustatean would bring out the colors.And add some more different food into their diet consisting of the massivore pellets,shrimps,crayfish,crabs,any other pellets thats big enough for him to see...and add some vegetables into the diet.If they dont eat it just put it inside of a meaty type of food that they love.Good Luck with yours..=)