I've seen it done a long time ago. It works, sort of. You can sometimes end up stunning the fish instead of killing it so it will be alive and breathing but it won't swim away from you when you try to catch it.

Though the machete or switch would work, especially coming down on a school of small fish in shallow water, a spear, when used correctly has the advantage.  Light refracts on the surface of the water, so what you see below isn't where you think it is.  An experienced spear fisherman will stick part of his spear gently into the water prior to striking.  The spear will appear to bend where it enters the water... this "bend" gives you the correct angle of refraction and you can actually hit what you're aiming for.  You can't do this if you're just chopping down onto the water with something.

bare hands,  ive done this before in a pool where small minnows are stuck,  they are very elusive of course with those nerves of theirs I forgot what they're called but u cant approach a fish without alerting it of your presence.  also a dip net is better than nothing,  ive done this many time on smelts and large salmon,  and I say its quite effective.

i would think it easier and more efficient if you spent twenty minutes using your machette to build a sieve (sort of a primitive tennis racquete made from a switch and interlaced bark strips) and then just scooped the fish out. i've used this method dozens of times to great success.

Back in the good old days of feudal Japan they taught us how to grab fish out of the river without getting our hands wet.

fishing is the one food gathering activity that differs dramatically the world over. unlike a lot of other 'primitive' skill sets which, apart from slight differences, are very similar across the globe, fishing usually has its own unique method specific to region and type of prey. hooks, nets, spears, corralling, traps, poison, you name it are used in drastically different ways by different cultures. when looked at as a whole, the variety of methods is actually staggering. over the years, i've tried most of them in one form or another and found two that i think work the best for me. one is the Inuit style fish spear, which if one is patient, can bring in substantial meals fairly easily. and, two, the corralling method where you build barriers and a small damn and trap large numbers of fish in a tight area. this requires running water such as a stream or river and a considerable amount of labor, but it can produce enough fish to feed a LOT of people. i say, whatever works for you and puts dinner on the hut floor is a viable method. the trick is not to expend more energy than you are potentially going to bring in.