Sometimes darkening of colour, such as turning to black more around the body and head, possibly lethargy and a more placid betta.
Mulan: Blue/Green/Red HM Male
Those who now swim in the Rainbow Ponds:
Spike: VT Purple Male
Glaedr: CT Yellow Male
Ezio: DeT Dragonscale Male
Stu (Founder of the obsession): CT Blue Male