I have an established fish only tank. I have a relatively large Naso tang I’ve had for years and a Tomini tang that I’ve had for about 2 years. They get along just fine. Suddenly, they’re both huddled in the back of the tank, the Naso tang is vertical, and the tomini tang is facing the opposite direction and rubbing on the Naso. The naso looks distressed (very dark in color and forming white splotches that fade away and then re-emerge). I rearranged the tank once and the naso got stressed and exhibited this stunned/splotchy behavior which is why I think she’s stressed. Do I have a pair of horny tangs trying to do business in the back of the tank, or is it something else I should be worried about. As I’m writing this, the tomini just approached the naso and shoved its butt in the naso’s face and started shaking. I’ve never seen them do this before and it’s just very bizarre.