Frank couldn't breathe ...

Frank couldn\'t breathe underwater. But where was he? Percy turned in a full circle. Nothing. Then he glanced up. Hovering above him was a giant goldfish. Frank had turned -clothes, backpack, and all- into a koi the size of a teen-aged boy. \
Frank couldn't breathe underwater. But where was he? Percy turned in a full circle. Nothing. Then he glanced up. Hovering above him was a giant goldfish. Frank had turned -clothes, backpack, and all- into a koi the size of a teen-aged boy. "dude." Percy sent his thoughts through the water, the way he spoke to other sea creatures. "A goldfish?" Frank's voice came back to him: "I freaked. We were talking about goldfish, so it was on my mind. Sue me.
 Rick Riordan

Quotes from the same author

“It’s natural to feel fear. All great warriors are afraid. Only the stupid and the delusional are not.”
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 Rick Riordan
The main courtyard was filled with warriors - mermen with fish tails from the waist down and human bodies from the waist up, except their skin was blue, which I'd never known before.Some were tending the wounded. Some were sharpening spears and swords. One passed us, swimming in a hurry. His eyes were bright green, like that stuff they put in glo-sticks, and his teeth were shark teeth. They don't show you stuff like that in "The Little Mermaid.
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 Rick Riordan
Everybody was patting Nico on the back, complimenting him on his fighting. Even the Ares kids thought he was pretty cool. Hey, show up with an army of undead warriors to save the day, and suddenly you're everybody's best friend.
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 Rick Riordan
Back up shall we? When my brother, the crazy chicken warrior, turned into a falcon and went up the pyramid’s chimney with his new friend, the fruit bat, he left me playing nurse to two very wounded people—which I didn’t appreciate, and which I wasn’t particularly good at.
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 Rick Riordan
Aphrodite strikes again, huh? You're gonna be the best-dressed warrior in town, beauty queen.
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 Rick Riordan