It wasnt until I started diving with real experienced guys that I learned how to truly stalk fish. As it turns out more than 90% of the fish I shoot now I hadnt even seen until I was on the bottom. The trick to diving in hawaii is not to chase fish but to let the fish come to YOU. (with the exception of diving holes and caves). Basically you want to spark a fishes interest.
I will find a spot that I think a fish would like, i.e. a sand patch in the middle of a reef, a channel in between coral ledges, deeper drop offs, archways, and cave openings. I then drop to the bottom as quiet and still as possible (longblades and proper weight are key), kind of like a sinking log. On the bottom (be sure to do a quick scan for any nearby wana or eels) I try to lay as flat and still as possible. For species like Mu or uku you want to try to completely hide your body. When they see you disappear into a hole, or low part of the reef they cant help but to come see what your doing.
etc etc etc
All good points here from Fleshy, Blaiz and Fondueset.
Blaiz gave you a brief, perfect description of the hunting style we europeans call "Aspetto", which simply means
"waiting". That's the most productive technique and I wish you to learn it successfully, but at the same time I feel somehow I must warn you about the
risks.
Now the problem with "waiting" for fish to come close, is that it
might require a long, sometimes very long breath hold time, exposing you to the risk of
blackout, especially for newbies who lack both a stealthy ambush technique and a good breath hold capability.
While you're waiting and waiting, and you feel you're running out of oxygen but those damn fish don't bother to come by, you will try to resist and might
say to yourself: "five more seconds, five more seconds, come on, five more seconds then I give up".
Till suddenly your brain decides that the air is really out, and it turns off all your non-vital functions such as moving your arms and legs. Some rescue diver will find you still there on the day after, or months after you will be
washed on some beach, dead as can be.
My suggestion, provided if it might work or not with hawaiian fish and hawaian bottoms, is a different technique called "agguato", which practically means to take fishes by surprise.
You may alternate agguato'ss with brief aspetto's (the waiting) till you improve your skills for longer aspetto's.
Here it rolls:
The fundamentals of AGGUATO:
You have to dive to the bottom BEFORE seeing the fish, and then after, once you're down on the bottom you start to look for them.
Dive very silently belly-crawling on the bottom, with minimal fin strokes or no fin strokes at all, using your free hand to grab rocks and kelp to help the crawling.
Swim large silent loops around kelp bushes and rocks, stopping every little while to have a look around, and every while TURN, make a curve around the rocks and bushes trying to take by SURPRISE the eventual fish being behind the obstacle.
If they're there at range, aim and shoot. If they're too far, lay very flat on the bottom, still covered behind something, and wait hoping they will come closer, using the tricks that
Blaiz suggested.
If you scare them, they will disperse far away, but don't lose hope: most of reef fish are curious and territorial, and many times they will just swim a large loop around and then get back to you, for investigating about you.
This time they're more likely to come at range, because their initial fear of your vibrations will be methabolized and they'll feel more self assured.
Of course, waiting for them to come back might require a long breath hold. If it's too much, just surface very silently, ventilate for as long as necessary, then go back down very silently to the place you were at before. If you're lucky, the fish are coming back to the same place. It happens sometimes.
Fish in schools
It's very difficult to hunt fish when in schools/groups, because schools always have a sort of sentinel alarm system: if you scare one, you scare them all.
Once they get nervous, they start swimming faster and you will certainly get jammed by all those fishes dispersing around, and you will loose precious time trying to make a decision on WHICH ONE to shoot among the lot.
So the best thing, even if they are dozens, is to focus on ONE single fish, track him calmly until he comes at range, and never change target, unless your first target fish disappears.
Shooting:
If they come in schools or even small groups or pairs, NEVER target the first one of the row: if you aim to him and he detects you, he'll get nervous. And, for being the first one in front of the row, he will immediately scare all the others following from behind because they will all see or feel him accelerating.
If the fish come towards you frontally, don't wait for him to turn on a side, but shoot him straight to his face.
Take care,
Spago