I have always bonked fish to stun them, slit the gills to bleed them, and popped them in the cooler with ice. When I go with one of my fishing buddies in his boat, he bonks them several times, puts them in an uninsulated fish box, fills the fish box with water, and leaves them all day.

Any suggestions/or info I can share with him to consider a different system? It seems like his system results in partially "boiled" unbled fish. He is pretty set in his ways, so any tech info that provides the food handling basis for something different may be helpful. thx.