Investigating the mysterious disappearance of two teenagers, an insurance adjustor named Maggie (Menzies) and her backwoods guide Paul (Dillman) discover a dangerous secret living in a nearby lake.

Seems a research scientist (McCarthy) engineered a super hostile, ravenous new breed of deadly pirahna fish for use as a military weapon in the Vietnam War (!).

After the war ended, the project was terminated. But the doctor kept some of the pirahna alive.

And now the vicious fish have escaped, are spawning like crazy, and are headed for a kids' summer camp and water park!

Can Maggie and Paul track the tiny horde of killers and stop them before hundreds die?

With lots of blood, boobs, and gore, who cares?

This blatant imitation is no classic, but it's a lotta fun, thanks to some hilarious performances and loopy plot logic.

Menzies and Dillman are good, but it's especially great to see scream queen Steele in a role as a government scientist hoping to stop the finny little beasts.

Director Joe Dante - who would go on to direct The Howling (1981) and a segment from Twilight Zone: The Movie (1983) - does an admirable job of keeping things moving along a nice clip.

It's nice to know Steven Spielberg has a sense of humor: Pirahna ranks as his favorite rip-off of his 1975 classic.