Blood Lake: Attack of the Killer Lampreys
After chomping through the fish population, thousands of starved lampreys begin attacking the citizens of a sleepy lake town, and the community scrambles to stay alive. (IMDB Summary.)
It's from The Asylum. It's pretty much what you expect from the summary.
I'm semi-cheating listing this here, because I wandered off during part of the movie to peek at the cooked grapes I'm draining of juice for jelly. But again, The Asylum; you don't need to pay attention to plot.
And, please let there have been a fad in Hollywood for starring in terrible movies as a joke. Otherwise, poor, poor Christopher Lloyd. :(