Hi, this could be spawning behaviour.
Can you see the breeding stars on his gills, perhaps?
Ours do that too, sometimes it looks like a "ball" made of 3 fish, hahaha, they swim in circles, above and below each other so you don't know who's head belongs to who's tail

I got the impression that our Humphrey starts to develop those pimples on his gills and also some tiny ones on the his pectoral fins, on the first ray.