Aiming the Spear gun

 Guys new to the sport will find aiming a good shot at a fish takes some practice no matter how “accurate” the new gun is even though it is substantially slower than a rifle shot.
Generally the range of the spear is 2-3 times the length of the gun with the first two thirds its effective range, the further the distance from the end of the muzzle, the spear quickly loses momentum and at the end of its range (usually governed by the length of line between the muzzle and back of spear) it sinks. Therefore the closer you are to the target, the better the accuracy and of course where you have aimed your shot on the fishes body.
Gamefish especially are constantly moving so the spear usually penetrates a few centimetres back from where it has actually been aimed. Reef or bottom fish offer a slower target and in the case of rock cod, stationary at times with a ‘head on’ shot or when a fish is hiding out in a cave.
The best position to line the speargun up on a fish is at ‘eye level’ (take care though the recoil doesn’t hit you in the chin or face if the back of the gun is too close) however this is not always possible and most spearos line up the spearpoint at a lower angle, A term called `refraction` - is where you think you are aiming squarely at the fish but in actual fact because of the angle the shot is off the mark. Many a spearo has had the frustration of missing fish after fish.
With practice one can perfect ones shooting, but actually landing the fish will also depend a lot on where the spear has hit the fish on its body. Make sure also the barb is treaked and opens correctly -in the probable event the fish will struggle.
Ideally the spear hitting the spine or brain will result in a kill or ‘stoned’ shot otherwise the middle to upper region is the next best preference. A shot too high on the dorsal area will result in a `tear off` with the fish struggling in most cases and a shot too low a similar result, especially around the soft stomach region.
To get the perfect shot, the rule of thumb is to line the spear up along the same level as its eye where the spine runs from the back of the head to the tail laterally. The closer the shot hits to the head (and brain region) along the spinal cord, the result will be a greater and quicker immobility (or a instant kill or stone shot -breaking the bony spine and ‘nerve system’ immobilising it immediately irrespective of size.)
As spearfishing is one of the most sustainable ways of fishing, spearing and not landing the fish is wasteful whilst the perfect kill or ‘stone’ shot increases the chances of landing that fish and avoiding a lengthy struggle or loss altogether.
Of course not every aim will be a hit and even the best of spearos can miss the target altogether, especially when the fish ‘spooks’ at the last split second and actually hears the trigger release the spear.
The perfect shot can be achieved with practice and knowing the `feel` of your speargun with the right rubber power to spear ratio.
It is also a formidable ‘weapon’-never point it at anyone, don’t rely on the safety catch and unload it before putting onto a boat.