The Thirteenth Year [VHS]
A fisherman chases a mermaid, she "temporarily" stows her  newborn on a boat, the owners find the baby, and thus begins young  Cody's life on land. Fast-forward to the kid's 13th birthday when he  starts growing scales and sparking electricity. (Of course, that would  make it the 14th year, but who's counting?) His swim-team stardom is  threatened, his girlfriend is puzzled, and the nerdy brainiac who can't  swim turns out to be his best ally. This tale of a popular dude who  turns into a mer-boy and finds his undersea self--and biological  mother--began life as a Disney Channel movie and stars Dave Coulier  (TV'sFull House) as the adoptive dad. Don't look for deep  lessons during this 88-minute lark; it's strictly for fun. (Ages 5 and  older)--Kimberly Heinrichs