Porcupine Puffer not eating

I have a porcupine puffer that I have had about a year. I recently moved him
to a larger tank and he has stopped eating. Previously he was eating
freeze-dried krill very aggresively. Since the move he just pokes at it and
will nibble a little but he has an obvious weight loss. I have tried some
frozen krill and shrimp pieces and even danced them around on a skewer in
front of him. Any suggestions?
Thanks
Dave Young