Perna viridis, known as the Asian green mussel, is an economically important mussel, a bivalve belonging to the family Mytilidae. It is harvested for food but is also known to harbor toxins[citation needed] and cause damage to submerged structures such as drainage pipes.

It is native in the Asia-Pacific region but has been introduced in the Caribbean, and in the waters around Japan, North America, and South America.

Perna viridis ranges from 80 to 100 millimetres (3 to 4 in) in length and may occasionally reach 165 millimetres (6 in). Its shell ends in a downward-pointing beak. The smooth periostracum is dark green, becoming increasingly brownish towards its point of attachment (umbo), where it is lighter. Younger mussels are bright green and that becomes darker as it ages. The shell’s interior has a pale-blue sheen. The mussel has a large mobile foot which it uses to climb vertically should it be covered by sediments. It also produces byssus to help it attach to its substrate.

The Asian green mussel is found in the coastal waters of the Indo-Pacific region. However the mussels are introduced to other areas as an invasive species via boat hulls and water ballasts.

The mussel inhabits estuarine habitats and is found in densities as high as 35,000 individuals per square meter on any submerged marine object. Although vivid green in appearance, the mussels are shrouded with overgrowth and are often hard to find.

This mussel is a filter feeder that feeds on phytoplankton, zooplankton and suspended organic materials. They are eaten by fishes, crustaceans, seastars, octopuses and humans.