I don't know what's wrong.
He suddenly got clamped over the last hour or two, and he'll have periods of sitting still.
But then he'll be fine for a few minutes, and then he'll have another clamping fit and will gasp once or twice.
I don't have a water tester to test the parameters, but I should still be good considering the tank had some old water from home and water from here and was treated with water conditioner.
He's also made a habit of squeezing in this small spot between the divider and the skull. (the skull props the divider up). He looks stuck before squeezing himself out. Could that bee damamging him?
He has these black marks on his side so I wouldn't be surprised...
I noticed that when he backs away from me, instead of doing it fluidly, he'll move in these jerky movements. It could jsut be me assuming things wrongly, but I don't know...