if it's just his barbels he's missing it may have been a water quality problem or wrong substate (too sharp) in the tank where you got him from - just by feeding him up and keeping him in your tank with the good water quality should make some major improvements - if he's skinny little meals more often(2 x daily) would possibly help....... my cories go nuts and get big and fat with frozen bloodworms and spirulena wafers (they prefer hikuri)
good luck with him
sue