The movie, featuring British beauty Kelly Brook, Elisabeth Shue and Jerry O'Connell, made $10 million (£6.6 million) at the U.S. box office over the weekend (21-22Aug10) and finished up just outside the top five films.
But movie executives at Dimension Films didn't need to see the figures - rave reviews prompted them to press on with a sequel.
Producer Mark Canton says, "We are thrilled that audiences are not just loving Piranha 3D, but cheering for it. And it’s fantastic that so many critics are really getting the movie and recommending it. We can’t wait to get to work on the sequel."