Chinese Hi Fin Banded Shark Question

[Loganfish]

Hello! I recently finished removing all the Fritz Coppersafe from my 55 gallon and filled it back with clean water. Before hand during the treatment, I moved my Chinese Hi Fin Banded Shark to my 20 gallon temporarily. The temp in that tank is room temp (65-75ish degrees F usually). Then fast forward, the started to acclimate it back into my 55 gallon. The temp is about 70-72ish degrees F in there. Since I acclimate it back into the tank, it likes to hand out near the top, at least during the day. I can’t quite recall if this is normal when, like when I’ve moved it around before. Any ideas and/or thoughts?

 

[Fishman Dave]

Is it alone in there and no reason to be so high or is it with other fish so temp is set. These fish prefer the lower range temps and hence higher oxygen saturation. Could be of course he is still sensing something not right in water quality. Even something as simple as dechlorinator, as I believe they are quite finicky with water.
My concern would be that these things should quite quickly outgrow a 55g tank and longer term need a temperate pond