I know that the original spearfishing is hand powered spearfishing. But for that the arm and the spear are initially outside the water. I also know of hand powered spearfishing underwater. It's more common with fish that hole up. My first spearfishing experience was actually with a hand spear underwater. More difficult is trying to spear free swimming fish but it's also possible. The problem is that the arm movement creates a pressure wave which most certainly makes the fish move before the spear ever finds it's mark. I've read that the best chances of success is to poke at a fish when they're facing/looking straight at you, when they turn to escape you have a chance of hitting them broadside since the spear is already in motion.
I came across this pic. Do you think this kid has any chance of spearing something this way?
