man thats a tough one...im not too sure what it could be...it could be that he/she is still settling down in the new enclosure but pixies usually dont tank more than a day or two to start eating like a machine again...well at least my frogs didnt...i know my one male went from a 10 gallon to a 40 gallon and went totally nuts the first night...jumping hitting glass and going crazy...next day he was settled tho and started eating again....my guess is just wait a few more days to see if his old eating habits come back...good luck