Circling back to the beginning of the topic....
Fish of Fury is a tactic to use, but by its very nature it's not something to base your army completely around. It can certainly be a very good addition, but have some other tricks in your bag to use as well; as another stated, if your Devilfish are all shot down by a lucky enemy first turn, you may find yourself the shaken player, rather than your opponent. Have the FoF ready and available, but *always* have something else to do as well.
Depending on the size of your game, having a FoF squad or two wouldn't be a bad investment. Use it to support other elements of your army, whether in Crisis suits, Hammerhead tanks, or other methods of battle. Strategy, in this case, is the application of your chosen tactics to make your opponent play your game, and not his own. Do the unexpected on occasion, and save the FoF for those prime moments when you can expect to crack your opposition's confidence.
Long story short, don't put all the eggs in one basket!
Cheers!