yo quero bazooka?
While I've not been down deep specifically to shoot fish, I've seen some really, REALLY big fish in the lights. Interestingly, some of the more unique occurances happened in fresh water, Lake Tahoe, CA/NV, where I was working on some surveys of the local dams. Big friggin trout!! Then there are the times when leaving the bell where I stepped onto the curious grouper...
The thing that worries me aside from the obvious tech stuff, i.e., decompressing, going to gases, support, etc., is the mindset that these fish get into when they get the shaft. As pointed out, these things take on the persona of pissed-off dinosaurs and if they're not immobilized, act very much, well, exactly like a buddy in distress- he's coming for you! If you're going to go this route, I'd recommend knowing the basic tech stuff and arranging on having at least two support people in the water- one to help you and the third to help both of you. And think really strongly of carrying a bangstick, powerheads or compressed air gun to nuke these things first shot. While riding behind a halibut might seem at the surface, (aww, bad pun!) to be the next wave in bullshit extreme sports, I'd consider myself really lucky to have hit one that didn't take off with me in the shooting line. I hear they like it really deep, and having shot smaller 20#ers and seen what they can can do, I prefer the shallower and smaller stuff.
When do we go?
sven