Piranha Part Two: The Spawning (1982)

In a Caribbean island, a couple is found dead inside a sunken ship. The scuba diving instructor of the local resort Anne Kimbrough breaks in the morgue with her acquaintance Tyler Sherman and finds that the bodies have been eaten in many parts. They have one night stand and Tyler tells her that he is a biochemist that have developed a specimen of genetically modified piranha capable of flying to be the ultimate weapon.