Is Charlie Betta sick?

[Biff and Fish]

Yesterday I noticed a spot above Charlie's eye. It's still there today. Maybe it's just me but I felt like he wasn't very excited about his food this morning and he seems to be less active than usual.

Does anyone know what this spot may be? Should I be worried? Should I treat it?

Please help Charlie !

 

[Biff and Fish]

My bad . . .

The vid didn't upload.