Ok, Ghoul is starting to worry me.
For about 2 days now he keeps staying 80% of the time in a corner (the same one), and he's lethargic (right now I had to tap on the glass to get movement out of him).
He doesn't show physical signs that something might be wrong, plus he does patrol the tank (or parts of it) from time to time. After that, he just comes back to this corner. This corner is part of a side where I have another aquarium with vivid fish in it (Guppy males and Lich, the Betta that I salvaged the other day). At first I though he's sad because he wants to play too, but he doesn't patrol the whole side, he just sits in that corner so I'm not sure.
Not sure what could be wrong and I have no water testing kit at the moment sadly. What I can say is that the tank went through a 100% water change yesterday (this problem started happening before that, so I don't think the change is what's doing it). Basically, he doesn't seem to be happy. I'm looking at videos of beautiful Betta males and I see them running around, and Ghoul moves like he's a man in his eighties.
He does eat, if that helps.
PS: He sits in a top corner, not bottom. Water temperature is constant at 78-79