I am currently feeding my 4 inch red wolf fish half a night crawler a day. Are night crawlers a good staple diet? I will also throw a market shrimp in there on occasion.
IMO you should try to get him on something a little more well rounded like pellets while he is still on the smaller side. Then feed earthworms, shrimp, etc as a treat.
Red wolves from my experience are not all that picky and will eat pretty much anything...
My reds loved Hikari pellets and beefhearts. I gave them superworms and ghost shrimp as treats but like fishinman said they will eat just about anything.