Thanks for the advice with the treats!
Herman update: I cleaned his cage. And he had a reaction to it... pics below...
1: Caption: I must cover my food dish to hide it
https://imgur.com/gDDYrB0
2: Caption: If I sit on my food dish for sure you cannot know food is there...
https://imgur.com/bXvKMsk
3: Hi mom. Let me lick you.
https://imgur.com/QlF0WyF