Asian date mussel or bag mussel


The Asian date mussel or bag mussel is a relatively small species of saltwater mussel attaining a maximum length of 3cm. It has a smooth, fragile shell, olive green/brown in colour, with unique zigzag markings and iridescent radiating bands.

Its habitat ranges from intertidal to subtidal habitats to depths of 30m, forming dense clumps in soft sediment or on hard surfaces. It can foul artificial structures and compete with native species for food and habitat.


Asian date mussel or bag mussel / Musculista senhousia

Key features:
  • Smooth fragile shell up to 3cm long, olive green/brown colour
  • Shell has zigzag markings and iridescent radiating bands
  • Often in clumps of many individuals
Known locations:
  • Found in Vic, SA, Tas and WA
  • Not known to occur in NSW
  • Soft sediment or hard surfaces
  • Occurs just below the low tide level in aggregated clumps
  • Fouls man-made structures
  • Forms dense mats competing with natives for food and space
Asian date mussel


Similar native species

These native species may be confused with this marine pest.

Blue mussel / Mytilus galloprovincialis planulatus

Key features:
  • Large fan shaped shell up to 12cm
  • Blue/black colour
  • Usually found in clumps
  • Sheltered and moderately exposed reefs, pylons and pontoons
  • Up to 15m depth

Brachidontes rostratus

Key features:
  • Long flat shell up to 4cm
  • Purple colour, regular rounded ribs
  • Usually found in dense clumps
  • Exposed rock platforms

Hairy mussel / Trichomya hirsuta

Key features:
  • Numerous hairs on lower half of shell
  • Up to 6cm
  • Exposed reef up to 15m depth
  • Common intertidally and subtidally

Little black horse mussel / Xenostrobus pulex

Key features:
  • Small shiny inflated shell up to 2.5cm in length
  • Black colour
  • Forms dense clumps
  • Exposed rocky shores
  • Mid intertidal





What is DPI doing?

On the 1st July the NSW Government implemented the new Biosecurity Act 2015 (the Act). Under Schedule 2 of this Act the Asian Date or Bag Mussel is declared as prohibited matter in NSW. This means it is illegal to possess, buy, sell or move this pest in NSW. In addition, NSW DPI has the power to seize and require their destruction.

People are expected to have a basic level of knowledge about the biosecurity risks they might encounter in their normal work and recreational activities. All community members have a general biosecurity duty to consider how actions, or in some cases lack of action could have a negative impact on another person, business enterprise, animal or the environment. We must then take all reasonable and practical measures to prevent or minimise the potential impact.

How can you help?

Learn to recognise, and be aware of, the Asian date mussel or bag mussel so that you can report any suspected new sighting.

If you see this pest in NSW, please report it immediately

  • Note the exact location
  • If possible take a photo and/or collect a sample
  • Freeze sample in a plastic bag
  • Report your sighting