I would say he is just getting used to his new environment.
it will take a couple days for him to start feeding again ( i would try bloodworms later on ).
BUT i do see a problem... fish need hiding spots to feel comfortable and safe or they will be stressed to death.
So i would go out to the store and buy some plants, driftwood, and rocks. If you do buy this stuff he probably
will start eating in about 1 or 2 days.
Hope this helped