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This section provides links to guidance documents that have been produced by a range of organisations.  While this information should be a useful resource, the Non-native Species Secretariat cannot endorse any guidance. If you would like to recommend management information to include here please contact us.

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Didemnum vexillum (Carpet Sea-squirt)


Dikerogammarus spp (Killer shrimps)

Dikerogammarus villosus

Dikerogammarus haemobaphes


Dreissena polymorpha (Zebra Mussel)



The New Zealand flatworm is a non-native species, first recorded in Great Britain in Edinburgh (1965), but now widely distributed throughout much of Scotland and, to a lesser extent, northern England.

A Code of Practice has been produced for this and other non-native flatworms in GB. This is a practical guide to help producers and traders of nursery stock detect and limit the spread of non-indigenous flatworms, notably the 'New Zealand' flatworm, Arthurdendyus triangulatus, and the 'Australian' flatworm, Australoplana sanguinea.

Non-native Flatworm Code of Practice (PDF)

Follow the links below for additional resources and information about these species:

Invasive Alien Species Fact Sheet (PDF): Arthurdendyus triangulatus - NOBANIS

Invasive Species Compendium: Arthurdendyus triangulatus (New Zealand flatworm) (external link) - CABI website 


Pacifastacus leniusculus (Signal Crayfish) and other non-native crayfish