Not really. It contains none of the same characters, and it doesn't seem to be a continuation of the first film in any way (with the exception of the character of Annie making a reference about piranha attacks in a lake in Texas a few years prior). Although the implication at the end of the first movie was that the piranha had reached the ocean, in this film they are there because a military study has accidentally dropped a canister of the fish eggs into the ocean. Furthermore, athough it does involve genetically altered fish, they're not really even piranha. They're actually a gene-spliced version of the flying fish and the grunion.
