Identifying frog species

Hey guys!
I work at a LFS up here in alaska and we often get a lot of mis-catch animals when we get our shipment of feeders.
I often take home the tadpoles that survive the shipment and raise them. My latest one recently finished his metamorphosis and I can't tell what kind of frog he is. Most of the ones that survive end up being common tree frogs but this guy looks a lot different than anything I've seen up here.

Any ideas?

Sorry about the super late response!
I'm thinking he's a bull frog. The person I gave him to has reported that he turned into a "tiny tank that eats like a monster"
His tadpole form, along with the new tadpole I got recently was between 2-3 inches long. Way larger than most of the ones i've raised before.
Thanks for everyone's replies!



This picture looks like both of them, not my picture though,just a very similar one that I found online. I'll post actual ones if I can recover them from my water logged phone!