Thankfully, there's nothing wrong with Robert (other than his psychotic personality). But one of my friends has a fish that is not doing well. I've told her to upgrade his tank already, she says she has no space. He's in a one and a half gallon tank at the moment. I'm not sure how often the water is changed. Anyway, here's a photo of him. She says he's completely changed color since she got him.
What does that look like? Any suggestions on what I should advise her to do for him?