I also agree with the fact that he should not be in a 180g tank, however its almost like he does not want to be in the pond. I am going to do like the others mention and make caves, hiding places and add plants and stuff and hopefully that does the trick. If not, I do not know what else to do.Welcome aboard
I agree withCaveden also as fish mature feeding habits and moods may change. Great to hear the Redtail Catfish is eating.