Originally Posted by Kawasakired
He is in a 3 gallon tank with a heater, air stone and live plants. Is this normal activity? Its only his 2nd day in his tank.
A 3 gallon tank with an air stone? You probably have way too much water agitation for your betta to build a bubble nest. Also, it's only been two days, he might still be adjusting to his new surroundings.
Remove the air stone, and give him some time to adjust. Be sure to keep an eye on his tankmate - they seem fine now, but your betta might forgo building bubble nest and instead spend all his time trying to chase the cory away. Unfortunately, both are confined to a small 3gallon aquarium! You should get another tank for your cory, and get him some cory buddies so your cory can go to school :)