are you sure he wasn't shedding his skin? is the frog skinnier, or just eating less? if it's winter or getting colder it's normal. if not, try feeding all sorts of food, crix, pinkies, mealworms, superworms, earthworms, night crawlers, moths, snials, slugs, anything you can think of. mist it a lot, they like that. whites are pretty hardy, so i'de just see what happens.
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RES
WTF
FBT
Russian Tortoise
Hingeback tortoise
Leos
Lawsons Dragon
Aussi
Ocelot Gecko
0.0.3 Vietnamese Mossy Treefrogs
Oregon Newt
Japanese FBN
American Bullfrog
0.0.4 D. tinctorius
D. auratus
D. leucomelas
D. imitator
0.0.2 imitator intermedius
D. lamasi
Grandis Day Gecko
Mali Uro
Hedgehog, bunnies, dog, fish, crawfish...