I've just updated the fsh.jar binary. Included in the latest version:
Laser sharks now prefer targeting ninja fish, and can "see" them from farther away.
Sharks are now more agile.
All predators have improved acceleration calculations. Meaning they're more likely to actually hit their target.
If two fsh that are capable of killing each other collide (within their kill areas), the bigger fsh wins. If the collision occurs in the kill area of only one of the fsh, that fsh wins.