Just got glofish tetras. New to them in every way. Does anyone know if different color tetras have this orange spot on top of their head? Or is it always a sign for something I need to address? Eats, poops and chases with vigor. Otherwise seems happy. Some have it and others don’t.
Yes it's normal.
Pretty sure that is their brain cavity, perfectly normal IMO. Some of them may have enough pigmentation to hide it, others may not.