My tiger oscar has been sulking in the corner of the tank, she'll swim but it's a soft sad swim if you understand what I mean by that. She isn't speed swimming it's slow and reserved to to the left corner of the tank. She doesn't swim long before pinning herself back at that bottom. I did a water change day before yesterday and moved some stuff around and she's done this before but it's worrying me more than usual. It didn't bother my other two fish in the tank, they're acting normal.