Goldfish looks very poorly. What to do?

[smokeybacon]

Goldie the goldfish is lying on his side, no movement. Gills look inflamed and twithchy. Mouth still opening.just. There is what looks like a trail of poo out of him. He's on his way out, isn't he? Do I leave him? Would he be in pain? Or do I hasten the process? Not me, I couldn't. I feel terrible for the poor wee thing. Any suggestions?

He sounds in a bad way :( Do you have water test results? How big is the tank? When's the last time you did a water change and filter clean? How long has it been set up and how old is the fish?