Everybody has a dream they wish would come true, whether it's a wide-eyed boy staring into space, a teenager getting onstage at an open-mic night or a jaded adult clutching a lottery ticket in one hand and a note of resignation in the other. For the characters in "Aquamarine," the discovery of a mermaid inspires the most sincere of friendships, simultaneously fulfilling two childhood wishes.

In real life, actresses Emma Roberts ("Unfabulous") and Sara Paxton ("Sleepover") have seen many of their dreams made real. And although she's no slouch in the entertainment business, Joanna "JoJo" Levesque is discovering that her newest friendships are helping to support her latest fantasy: that of becoming a movie star.

"This is my first [movie] interview!" the barely-15-year-old shrieked recently as she discussed her film debut with MTV News. "I'm glad the two other girls are here, because we kind of feed off each other. And that makes it a lot less painful."

Although she's been acting and singing for years, JoJo has been careful in preparing her transition to film, beginning with this month's family-targeted mermaid flick and carrying into April's road comedy "R.V." With her mother standing nearby and Roberts, 15, and Paxton, 17, busily chatting her up before the cameras were turned on, JoJo undoubtedly felt right at home.

  JoJo, Emma and Sara At The Premiere Of "Aquamarine"
 "Aquamarine" Photos
"Aquamarine" Trailer
  Check out everyting we have on "Aquamarine."
"I've actually been acting since I was 6, doing professional theater and stuff like that in my hometown of Massachusetts," she explained, brimming with the self-confidence that has already helped her become a recording star. "So acting wasn't a new thing for me. But as far as film, it was new, and these girls are so professional and everybody was so great to work with. It was a first-time director. So we were learning things about each other and learning the ways of this film and the process."

Coming in for an assist to her younger, first-time co-star, the elder Paxton chimed in with an attempted breakdown of the flick: "The basic plot is two 12-year-old girls who are best friends, they ..."

The golden-haired screen mermaid stopped herself short. "Wait a minute. Are you guys 12?"

Looking back at her, Roberts and JoJo shrugged their shoulders and giggled.

"Well, OK, two girls, age unknown," Paxton grinned. "They are best friends and they find a mermaid in their swimming pool. ... They feel like outcasts. And my character comes along, and she's not from this world — she's from underwater, literally — and she brings confidence to them."

In real life, the stars insist, there are no such things as mermaids — just actresses in really tight outfits. "She looked really good in it," Roberts promised, soliciting a "Thank you, Emma" from Paxton.

"The first time I actually wore the tail, it was really weird, 'cause the tail's like 100 pounds or something, really heavy," Paxton reported. "So, five guys on a stretcher had to carry me everywhere. When I was in the full outfit for the first time and they brought me out on the stretcher, I felt like a princess. Everyone was clapping for me, and I raised a hand in the air and everyone's like 'Whoo hoo!' and then they threw me in the pool like a fish."

Peep the "Aquamarine" star's life and career, in photos.

"When you'd touch it, you'd think that it might be slimy," added JoJo. "But it was really dry."

Another difficult obstacle was the meticulous placement of Paxton's long hair, utilized by director Elizabeth Allen to conveniently cover up her naked lead character's, um, barnacles. "That was a problem," Paxton laughed. "Gosh, paint, Velcro, glue — like after five minutes they'd be like, 'Cut! We got to move the hair. Don't look at her; we've got to move the hair.' It was a big issue."

With all the fun they had watching Paxton wrestle with her tail, the stars realized that one of the film's wishes was indeed coming true in real life. "It's about friendship in unlikely places," JoJo said, perhaps referring to the action on both sides of the camera.

Shot largely in Australia, the film resulted in a special bond between its three young stars. "All we did was just go shopping," Paxton said, cracking up the girls. "And we went to the beach.

"We bought bikes there," Roberts added.

"We rode around town," JoJo chimed in. "Mine was red and blue."

"We couldn't do tricks 'cause I didn't have a bike," Paxton reported. "I rode on the back of Emma's, and we fell a lot."

"We actually have horrible chemistry," JoJo laughed.

"We actually really hate each other," Roberts added. "The first time I met Sara, I was so tired, I got off this nine- or 10-hour flight from L.A. and I walked into the production office and this girl is screaming and comes running at me and grabs me and I'm like, 'Oh my God, what's going on?"

"I was there a week earlier and I was all alone and I needed some companions," Paxton explained. "When they arrived, I was freaking out, I was running around screaming. And they're both like, 'OK, weirdo.' "

Soon, they were helping JoJo adjust to her first feature film, teaching each other the layout of the local malls and sharing a quick tutorial on the shoot's regulations regarding mermaid life. "There's definitely lots of rules," Paxton reported, listing the Gremlin-like restrictions. "I can't get wet, or else my tail will pop out. And I can't be out past night, because the moon makes my tail come out again."

"Underwater, there are arranged marriages," Roberts added. "There's no love."

"So we're trying to help her find love as a human girl with legs," JoJo jumped in, adding that if the girls help Paxton's mermaid, they're guaranteed a wish.

Cracking her co-stars up, Paxton posed an age old question: "Can you wish for another wish. Or, like, infinite wishes?"

"I always wondered that," Roberts grinned. "Have you heard that rule in every movie? It's like, you can't wish for more wishes."

"I'd wish for world peace," JoJo insisted, "You know, that whole thing."

Paxton offered no such lofty ideals: "I'd wish for a gillion dollars."

"If we had that logical thinking, maybe," JoJo countered. "We don't. But then there'd be no story, and it'd be over. It'd be a five-minute movie."

JoJo cracked herself and her co-stars up with the frank assessment. Maybe they don't have a gillion dollars, and maybe they haven't got a million wishes that will all come true. But like their characters, the three young actresses seem to have a genuine friendship — and there's nothing fishy about that.

Check out everything we've got on "Aquamarine."

Visit Movies on MTV.com for more from Hollywood, including news, interviews, trailers and more.