Hi Ihab,
Despite all that one thing is advisable in them all, whenever possible always make a head shot or as near to it as you can.
There are a lot of stories of cuda atacking speros, (i have been charged twice by the same barracuda once), but one thing is comon in most of them...the fish was speared and fougth back.
Its while retriving the fish after being speared that accidents happen.
Mid body shots allow barracuda to move their heads just the enought to bite a less cautious spero, while a well placed shot near the head allows you to grab the spear from both sides without no problems.""
I can confirm this advice. One of my friends was bitten in the leg by a big barracuda when he was retrieving it after a bad placed shot. He got 90 stitches, lost a lot of blood, but fortunately survived. So if you decide to shoot them, hit them in the head or as close as possible, and take control of the fish as soon as you can to diminish the risk of it attacking you. Good luck.