Hello, I just bought a 90gal salt water tank with overflow into 20gal sump. I have close to 80lbs of Live Rock. I'm hope to meet cool people on this form that might help me with tips to have a stable tank.
If a tang isn't swimming about there is usually an issue. Probably some stress because of territorial issues between the two tangs. I would consider getting rid of one of the tangs if this behavior continues.
Welcome to Living Reefs Dhanraj. Is your yellow tang better now? Probably it's a stress issue due to relocation, or territorial issues too.
Good luck!!