my tips for bass:
Try shallow water hunting them first and observe their behaviour! It will help a lot when you go after them in the 5-10M depths using many a short/long aspetto to get their attention
No finning allowed here, use the rocks/seaweed to advance using your left/right hand extremely slowly so as not to even create vibrations in the water.
You'll find bass up to 4+Kg in size if you manage to be discreet enough in the water and eventually, you'll stumble on one resting/eating/wandering, or preparing for a pounce themselves
Don't react to their presence by pointing your speargun towards them as they will instantly distance themselves, do it very, very slowly and you might not scare them off. Movement is your enemy when hunting bass. My favourite way to hunt them is in very shallow water at sunrise/sunset. Pretend you're an indian underwater and don't make a sound/vibration in the water, the element of surprise will have the fish on the end of your spear alongside playing on it's curious nature and the intrusion you have made into it's territory.
Find spots to hide and try waiting while looking dead centre with fixed eyes at the tip of your spear -- they'll come right onto the end of it and look you right in the eyes before you kebab em.
If you look at them they distance themselves -- no movement! You need to be v. patient for this to work but the reward is there if you are completely silent and motionless but most of all - well hidden -- especially the tip of your spear. This works as well in the seaweed looking out onto the sand, in water as shallow as 50cm depth.
My preferred method is the first -- advancing using my free left hand very, very delicately and slowly -- hoping to surprise them while they're eating, wandering, resting or waiting to pounce on unsuspecting prey themselves.
I've found them concentrated in the kelp/laminaria/angel hair/green spaghetti variety of seaweeds including whatever you call that slippery green one that covers some rocks. They love the sand and rocks too. I tend to do my aspetto at the limits of some rocks or seaweed, beside the sand or completely hidden under the laminaria using it to hide the threatening gun. I either check the holes in the rocks/seaweed or hide myself looking out onto the sand or back upwards from the sand. Or altogether on the sand/seaweed in open water.
Find spots where mullet seem to be concentrated, often bass will be in the same area, I've found they seem to use them for cover and often when looking into a school of mullet you might just spot a bass in there -- at the back of the pack more often than not.
If you see mullet when doing your aspetto, wait - don't take notice of them and if you remain motionless then you might just get some bass afterwards.
I prefer going after them with a 90cm tube -- 120mm spear - 6.5/7mm thick in diamater. Two guns I have at present are the Beuchat mundial and Sporasub's Viper 30.
Happy Hunting
edit -- try fishing at slackwater on the high or low tide or 1hr before either but there's no real golden rules here.
you might find a picture of a 2.5Kg one I took a few weeks back here
http://hoedic2004.lenivet.com -- Francois/CNIP