The Qu's Marshes and Frogs serve two purposes in Final Fantasy IX - powering up Quina's Frog Drop ability and providing Quina with better equipment. Quina can learn the Blue Magic "Frog Drop" from the Gigan Toads in any Qu's Marsh. The formula for how powerful the attack ends up is as follows: Quina's Level x # of frogs caught=HP Damage to enemy. Another benefit of the Frog Drop is that it's a non-elemental attack that never misses.

Now, as Quina catches frogs Quale will occasionally come out (no matter which marsh you're at) and give Quina gifts to reward the progress. In order to make sure that the marshes replenish quickly it's important to never completely empty a marsh. You always want at least one male and one female frog in each pond. To achieve this you should always leave four frogs in each pond and you should take an equal number of male and female frogs.

Also, you must never catch the Gold Frog. Leaving it will increase the speed at which the other marsh frogs reproduce. Should you leave a pond without a male and female frog it will take much longer for the pond to refill. The marshes will refill as you level up or progress the story. If you come back and there are baby frogs or tadpoles leave them alone and level up a few times and they'll have grown up. It's possible to catch 99 frogs. The rewards you receive for catching them are as follows:

Now, once you've caught frog 98 you should go outside the marsh and save your game. You're about to face the highest HP boss of the game. Once you return and catch the 99th frog Quale comes out and you're forced to fight him as your final test.

Although Quale has the highest HP of the game he is not the hardest boss of the game. However, he likes to use lots of status ailments. You'll want to equip these support abilities before the battle: Loudmouth, Antibody, Clear Headed and Bright Eyes. With that done you'll be protected against the worst things Quale can do to your party. He'll use mostly water based attacks so if you have anything that absorbs water attacks you'll be in even better shape. Finally, you absolutely want to steal from Quale because he has some awesome equipment. You're required to have Quina in your party so for the other two choose either Eiko or Dagger and one other of your choice. Make sure Zidane has Bandit and Master Thief on. Once he's stolen all the items just keep attacking Quale until you win.