Title: Luffy's Fishy Adventure

Summary: Luffy wakes up one morning only to find that his legs are replaced by a long fish tail.

Disclaimer: I do not own any of One Piece's characters.

Chapter 1

Luffy woke up and yawned loudly, stretching his arms over his head. It was early in the morning in Fiji Island, an island famous for its beautiful beaches.

The others in the room; Zoro, Usopp and Chopper were still asleep soundly. Sanji wasn't in the room. He was probably in the kitchen preparing breakfast.

At the thought of breakfast, Luffy happily jumped down from his hammock but instead he slipped and fell down from the hammock, landing with a loud thump on the ship floor. Luffy sat up and groaned, "That's strange. I don't usually…AAAHHHH!!" Luffy screamed when he found that instead of seeing his legs in front of him, he saw a long green fish tail in front of him.

The others in the room woke up when they heard him scream. Usopp, who was sleeping on the hammock under Luffy's hammock sat up. Rubbing his eyes and grumbled, "Oi, Luffy. Do you have to be so noisy every morning?"

"My-my legs!"

"Huh?" Usopp turned to look at Luffy's legs.

"Oooowah!" Usopp screamed, his eyes bulged out when he saw the green fish tail.

"EEEEEEEEEE," Zoro and Chopper shrieked and their eyes bulged out too when they saw it.

"Hey, what's all the screaming about?" Nami called out, coming down from the stairs into their room followed by Sanji and Robin.

Sanji and Nami screamed too except for Robin, whose eyes just grew wide in surprise.

Luffy raised his tail up and down as if testing it.

"Wow, amazing!" Luffy said, his eyes turning into stars.

"Oi, oi, don't you know how serious is the situation you're in?" the others asked in unison.

"How did this happen?" Nami asked incredulously.

Robin examined him with a thoughtful look on her face. Then she asked, "Eh, Luffy, try stretching your arms."


He was still able to stretch his arms like he always did. "Hmm…whatever that transformed you did not alter your devil fruit abilities."

"I wonder if he can swim," Usopp asked wonderingly. He went over and touched the scales on Luffy's tail. They felt like ordinary fish's scales, rough and slippery but quite tough. Sanji went over and lifted up his red vest to see how far the scales reached. The scales only reached up to his waist.

"So he turned into a merman," Nami said.

"A merman huh," Zoro said. "I wonder if he can swim."

"Do you think he'll drown because of his devil fruit ability?" Chopper asked.

"Well, there's one to find out," Sanji said, lighting his cigarette.

"Huh?" Luffy look at them questioningly.

Zoro lift him up from underneath his arms while Sanji lift Luffy's tail. Nami took his hat from him so he doesn't get his hat wet.

When they had carried him up onto the deck out under the sunlight, they saw there was a slight change in Luffy's skin as well. His skin seemed to be paler.

"Look behind Luffy's ears. Near the earlobe. I think those are gills," Chopper said, examining them. The others took a look as well and sure enough, he had gills similar to that of a shark. Three lines of gills keep opening and closing. They were small and hardly noticeable if you don't look closely.

"Ready for a swim, Captain?" Zoro asked.

"Yosh!" Luffy yelled, pumping his fists in the air.

With a great heave, Sanji and Zoro threw Luffy overboard. Luffy held his breath as he hit the water surface. He was still holding his breath when he was under water because he was afraid he might drown.

He tried swimming by moving his tail up and down like a dolphin's and it worked! He was swimming under the sea and no longer sinking downwards toward the sea bed.

"YA-HOO!" Luffy shouted joyously. Then he remembered about the breath he had been holding.

"Hmm? I can still breathe," Luffy realized he can breathe as easily as he was on land. He grinned broadly and swam towards the surface.

"Oi, everyone! Look, I can swim!" he called out as soon as he broke the surface. The others watched in shock and amazement as he swam around effortlessly and gracefully surging through the water. They were half expecting him to drown.

"Hahahahaha!" Luffy laughed happily as he swam around.

"Hey, isn't that the boy who came to our village yesterday?" a fisherman asked another fisherman beside him. They were heading towards shore with their fishing boat.

"Yeah, I saw him playing around the beach yesterday with his friends," the other fisherman said.

"Could he have eaten the Mermaid Fruit?" the first fisherman wondered out loud.

"Oi, you there!" the fisherman called out to Luffy. Luffy stopped swimming around and focus his attention at him.

"Did you eat a purple fruit with green spots on it?" the fisherman asked.

"Hmm…now that you mention it, I think I did. It's nice and very sweet," he replied, grinning at them.

"Where did you get it?"

"On the beach."

"So he did eat a Mermaid Fruit," the second fisherman said.

"Mermaid fruit!?" the straw hat crew cried in unison.

"Yeah, it's a fruit that turns humans into mermaids or mermen. They're rarely found. Legend has it that a woman from this village found this fruit and ate it and turned into a mermaid. And that was a hundred years ago," the first fisherman said.

"Why can't it be Nami-san or Robin-chuwan who ate the Mermaid Fruit?" Sanji asked dejectedly.

"Shut up!" Nami yelled at him. Robin chuckled.

"Wow, cool," Luffy said, with stars shining in his eyes.

"DON'T GET SO EXCITED!" the other members of the crew except Robin yelled at him.

"Okay, so now we know what turned him into a half man half fish but how do we change him back?" Zoro said, sitting down on the deck cross legged.

"Perhaps you should try finding some answers from the library in the village," the first fisherman suggested.

"Alright then, we'll go to the village's library to find out," Nami agreed.

Luffy tried to stretch his arms to grab hold of the ship to haul himself up but realized he can't. "Ahhh…I lost my powers!"

"I guess he still lose his powers when he's in the sea water," Robin said thoughtfully.

"Luffy! Stay near the ship and don't swim far away from the shore until we come back," Nami told Luffy.

"It's too boring just to stay around here," Luffy whined.

"Luffy, you it's not safe to go further and deeper into the sea. What if you meet a Sea King? You'll be a goner for sure," Usopp said.

"Oooooohhhh," Luffy whined.

"Luffy, they're right. It's best that you stay put," Zoro said.

"Hmph! Fine," Luffy pouted.

"Good. You better be in sight when we get back or else no meat for you tonight," Nami warned.

"Yes, Nami-swann!" Sanji cooed with his eyes turned into hearts and followed the others, leaving Luffy all by himself in the sea.

A/N: So what do you think? It's just an idea I thought out after seeing Kokoro in her mermaid form. I imagined Luffy in a form with a long fish tail and thought what many adventures he would have. Lol. Please read and review please!