Isn't the movie water horse like eragon>?

That wouldn't be saying anything because "Eragon" lifted most of its story~novel and film~from the Pern novels of Anne McCaffrey and other dragon works that went before it. The teenaged author borrowed liberally. "Eragon" didn't have much originality, and it's amazing the books didn't get marked as plagiarized material. At least "The Water Horse: Legend of the Deep" is drawn from Celtic myths and legends.

Anyway, the foundling story has been done many times before, so, no, it isn't like "Eragon"~~not anymore than it's like any other such story. Even in "Surface", the boy collected what turned out to be an egg and hatched it in the aquarium. So, is someone going to say, "Isn't 'The Water Horse' like 'Surface'?"

If you're curious about the legends, this site has some interesting information:
http://www.horsensei.com/publications/My...

The creature in the movie isn't quite how they usually are pictured, so the novelist took some liberties.

It sorta sounds like it but I haven't seen it coz it hasn't come out yet but not as much adventure and won't screw up a book and it's not a dragon and it suppose to be set on Earth

That would be no...
Eragon = flying around on dragons battling a force of evil
Waterhorse = some goofy kid with a big sea-horse in his bathtub.