How do I beat the Bonefin Galaxy Boss?
There's a giant fish named Kingfin in the Bonefin galaxy of Super Mario Galaxy.
How the heck do I beat him?
Solution 1:
There are two turtleshells in that level, a green and a red one. Use the turtleshells to swim towards him, and once you're within strinking distance, do a 'spin' attack so that you throw the turtleshell.
It takes 5 hits to defeat him.
After the first hit, he releases homing piranhas that come after you. Dodge these by making quick turns. There is also a power mushroom that gives you 6 health.