I went to check my temporary tank last night and found my XXL Pleco laying on his back

. My Opaline Gourami was acting stressed. So I went to get something to put it in. When I got back he was upright and had moved

. The water was low so I topped off the tank.
How long do Plecos live anyway? Mine could easily be 20 years old. Or is my temporary tank getting away from me again? I've already lost 3 smaller fish when the tank cycled 2 weeks after setting it up.
I thought that you needed a sledge hammer to kill these things:icon_wink .
Jim