An outstanding threat among the little “lobsters” now offered online by aquarium suppliers is the attractive marbled crayfish, or “marmorkrebs”, an aquarium-bred strain of an American crayfish species, Procambarus fallax forma virginalis. The last word conveys its particular menace. Marmorkrebs is parthenogenetic – its eggs develop without male intervention – and continuously produces young. How many crayfish does a home aquarium need before offloading into the nearest stream or pond? Like virtually all American crayfish, P fallax can carry and transmit plague, and it is already naturalised in several places in Europe.
There are a couple of notable things in this article. It’s the first time I’ve seen it given the full species name from Martin and colleagues (2010) appear in a popular article. Second, it states that Marmorkrebs carries crayfish plague as a demonstrated fact. This is extremely likely, but has never been conclusively tested, to my knowledge.