Since everyone is being critical of the holding your breath idea I figured I'd throw in another problem. If you are stalking the fish you'll have to tow the hookah float behind you as you move along (slowing you down) So it will probably severely inhibit your ability to catch up with fish or move quickly enough to spot them before they spot you. Then there is the option of not towing the hookah system and removing the regulator while you hold your breath...then returning to it after you shoot the fish or once you need air (this way you can stay down while still stalking and not let having to tow the hookah system around slow you down) FOR OBVIOUS REASONS THIS IS A REALLY REALLY BAD IDEA. If the fish pulls you too far from the hookah regulator you'll be stuck and forced to ascend (bad)
if you accidentally swim too far because you're not paying attention you could be forced to ascend (bad)
if the hookah float gets pushed away from wind or current you could be forced to ascend (bad)
I have thought about all of this because a friend of mine had one and I thought about using it for spearing. All in all it's bound to fail.
The systems are really good for treasure hunting/ recovery operations (which is one of their primary uses), commercial work under boats (their other primary use), then a lot of people use them to collect shellfish too. Other than these uses they are pretty limited. Oh and those women in the mermaid costumes in underwater shows at seaworld or wherever use them too
