Australian Aquatic Biological

Australian aquatic biodiversity research and consultancy

Freshwater leeches feeding on Crayfish

A WA Marron suffering from Leech attack

A WA Marron suffering from Leech attack

Freshwater blood and fluid sucking leeches can pose a serious problem for freshwater crayfish. Typically it’s the common yabby (Cherax destructor) that you find leeches attached to or they have a nasty round scar indicating a leech has had a feed. The scar remains until the crayfish moults but the scar itself can create difficulty in moulting and can lead to the death of the crayfish. From an aquaculture perspective, leeches in your ponds are a big NO-NO and every effort should be made to catch and remove them as the unsightly scars on crayfish make them unsellable.

The Marron and its leech attacker

The Marron and its leech attacker

Most leeches can ingest several times their own weight in blood at one feeding and swell to a large fat size. Leeches attach to their hosts and remain there until they become full, at which point they disengage and fall off to digest their huge feed. Crayfish are most vulnerable when they are freshly moulted. Freshly moulted crayfish are already stressed out and weakened by the moult process, the additional blood loss from a leech feeding could be fatal. This risk of mortality is greatly increased if the crayfish is small and the leach large.

Below North Dandalup Dam, WA

Below North Dandalup Dam, WA

The example Marron with a leech attached was found in the swimming hole below North Dandalup Dam, WA.

Images compliments of Tegan & Josh Moylan


Robert McCormack is the Research and Aquaculture Director for Australian Aquatic Biological P/L. He is a Research Associate with the Carnegie Museum in Pittsburgh, USA, is Secretary of the NSW Aquaculture Association Inc. and the team leader of the privately funded Australian Crayfish Project, which conducts biological studies of every creek and stream in Australia, collecting and identifying crustaceans. Robert has a passion for freshwater crayfish traveling across Australia to find and photograph them.


You can follow any responses to this entry through the RSS feed. You can leave a response, or trackback from your own site.

Tagged , ,

Leave a reply

Your email address will not be published. Required fields are marked *


This site uses Akismet to reduce spam. Learn how your comment data is processed.