White's tree frog hiding for a week

[noob]

ive had my white's treefrog for a week now and hes been hiding. is it because hes stressed going into a different tank or is it because i dont have a good setup? im just worried he will die on me if he doesnt eat soon . and on top of that i have a gnat problem they laid eggs in the tank but i got them out I dont know if this could be stressing him also.




this is what he looked like when i first got him






this is the tank with lots of green stuff its a 20gallon tank. has sphagnum moss(heard it was best) but i also got ecoearth bedding i can but in there if its better.