Why is my male betta burrowing in the rocks?

Your male betta may be burrowing in the rocks due to stress or a desire to create a hiding spot, which is a natural behavior for fish seeking shelter. It's possible that he feels threatened by other tank mates or environmental factors. Additionally, he could be exploring his environment or exhibiting nesting behavior. Ensure that he has plenty of hiding places and that the tank conditions are optimal to reduce stress.