I understand what you are saying... I have been able to solo in FB, but the trick is to make sure you only aggro one or two (max) at a time, and i'm referring mainly to the minion fish, and perhaps the 61's and 63's (which i've been able to do) provided its a one on one fight. Usually this requires some luck, or a couple of other groups taking on the Bosses, so you can isolate the stragglers.
Usually what happens, though, is once one fish goes aggro, a couple of others will follow, but if you back up enough they usually break their pursuit, or you have time to then go after the other once your first target bites it. Hense the problem with the grave link, so you need to be no closer than about 6.5k i've found..
I certainly don't have a problem with this being as difficult as it is in general, i just think the grav link lasting so long basically made it so you couldn't at least turn tail and run when you got in over your head. They would just tag team you, and you could just sit there and watch your ship go 'poof'...
If you shorten the grave link duration i think it will improve the game, while still not making it easy to fight in the FB on those days when you can't find a group to fight with.