Hi all. My betta currently lives alone in a ten gallon tank. For the past two or three days, he's taken to laying on his side at the surface of the water, either behind the filter intake or between the floating plants I bought for him. He seems fine in every other way; he eats regularly and explores the tank when he feels like it. However, whenever he just lays there, he looks very much dead. Other times, he lets the current carry him to the top of the tank and on his side. What could be going on? ETA: I plan on getting three cories in the near furture. Maybe he'll perk up then? TIA.