Simply leave the fish in its water and release it there, and because it remains untouched its mucosal layer is still intact so that it will have a better chance of surviving the dehooking operation. You can bet it will thank you in the end! (Video 6)
In summary: You can extract the hook without having to grip the fish to see how and where the hook is embedded, practically blind, without light - at night, for instance. No use of a jaw spreader, or netting, gaffing or fish gripper is needed for particularly viscous fishes. Your fingers will be safely away from sharp scales, thorns and teeth, and will remain clean, dry and warm even while ice fishing (Video 7).