Instructions
Go through the red door at the end of the level to face the boss, Bessie Bass. After the room partially fills with water, the battle will begin.
Dodge the boss by jumping between the three floating platforms as she swims around under the water. She will occasionally poke her head above the surface; again, jump away and make sure you don't get hit.
Fire an egg into Bessie Bass' mouth when she jumps out of the water. It's easiest to aim upward while the fish comes crashing down. Sometimes, Bessie will instead do smaller jumps. Rather than try to aim into her mouth during the short jumps, dodge instead, and wait for the high jumps where you will have more time to aim.
Eat more eggs if you run out of ammo. Eggs and Shy Guys will fall from the top of the screen during the course of the battle, so you don't have to worry about running out of eggs to shoot at the fish boss.
Jump after Baby Mario to get him back if you've lost him. If the timer runs down before you get Baby Mario back, you will lose.