Freshwater crayfish for lab examination

Images showing how to humanely kill and preserve freshwater crayfish

Humanely kill and preserve freshwater crayfish which are to be submitted for examination

If you have sick or dying crayfish and need to submit these for examination and diagnosis by a pathologist, this is what to do.

Select six or more sick crayfish typical of the problem. Similar samples will be needed from each pond/tank if several ponds/tanks are affected.

You may send live crayfish or preserved crayfish.

Option A - how to send live crayfish

Crayfish should be sent in an approved styrofoam esky. Keep crayfish cool and damp at all times. Use rolled-up newspapers or mesh onion bags as packing material in the esky to cushion the crayfish and to soak up any excess water.

Place a sealed ice container or frozen gel pack at the base of the esky. Wrap the coolant in some of the packing material to prevent crayfish coming into direct contact with the coolant.

Place the crayfish in the esky and tape the lid securely in place.

Fill out a specimen advice sheet and tape it to the top of the esky.

Organise transportation to the laboratory, so as to minimise transit time.

Advise the laboratory how and when the crayfish are coming.

Option B - how to send preserved crayfish

Use only live, sick crayfish for preservation

Caution: When handling preservatives, wear gloves and protective eye wear.

For crayfish (10-30 mm in length)

Place freshwater crayfish in a coolroom at below 4°C until it is insensible. A crayfish is insensible when the abdomen and tail can be easily extended or manipulated and the outer mouthparts can be moved without resistance.

Marine crayfish should be placed into an iced saltwater slurry at 1°C, made up of one part ice, three parts saltwater for a minimum of 20 minutes or until insensible.

The crayfish should be humanely killed by rapidly destroying the nerve centres. This is done by cutting through the centreline of the head and tail (splitting) (Figures D and E).

Place the whole crayfish into the fixative solution.

For crayfish (over 30 mm in length)

Place freshwater crayfish in a coolroom at below 4°C until it is insensible (see above).

Marine crayfish should be placed into an iced saltwater slurry at 1°C, made up of one part ice, three parts saltwater for a minimum of 20 minutes or until insensible.

Use a syringe and a 21-gauge needle to inject the preservative (preferably Davidson's solution) into the crayfish to preserve it.

Inject 1-2 mls fixative into the head (Figure A) and 1-2 mls into the tail (Figure B).

Cut off the head (Figure C). Cut out a segment of tail (Figure F). Place all these pieces into the preservative.

Ensure that there is 10 times the volume of fixative for each volume of tissue.

For preserving crayfish, Davidson's solution is the preferred preservative. However, if not available, 10% buffered neutral formalin may be used.

Davidson's solution

  • Glacial acetic acid 115mls
  • Formalin (37-40% W/V formaldehyde soln) 220mls
  • 95% ethyl alcohol (ethanol) 330mls
  • Tap or distilled water 335mls.

If there will be a long delay in sending the preserved crayfish to the laboratory, replace the Davidson's solution with 50% ethyl alcohol (ethanol) after 24 to 72 hours.

10% buffered neutral formalin

  • Formalin (37-40% W/V formaldehyde solution) 100mls
  • Distilled or tap water 900mls
  • Disodium hydrogen phosphate 6.5 grams
  • Sodium dihydrogen phosphate 4.5 grams.

Specimens may be held in 10% buffered neutral formalin indefinitely.

When you are sending preserved material to the laboratory, pour off the preservative. Place a piece of paper towelling or cloth around the specimens to keep them moist and to absorb any free preservative.

Place specimens into a plastic bag, remove excess air, and seal with heavy packing tape. There should be no free fluid in the bag. Place the bag and specimens into a second plastic bag, remove excess air and seal with heavy packing tape. There should be no smell of preservative from the package.

Label each bag if more than one lot of specimens is to be sent in the same box.

Place labelled bags containing the specimens into a strong cardboard or aquaculture-standard coolite box. Add packing to prevent specimens being damaged during transport.

Complete the attached specimen advice sheet, place it in an envelope and attach it to the exterior of the box containing the specimens.

Contact the relevant Aquatic Pathologist or Veterinary Officer before sending samples to the appropriate laboratory, as listed below.

If you need further assistance, please contact your nearest veterinary laboratory (refer below).

Submitting samples

Contact the Duty Pathologist before sending samples.

Submit routine aquatic animal samples for testing to:

Biosecurity Sciences Laboratory
Health and Food Sciences Precinct
Specimen receipt (Loading Dock 12)
39 Kessels Road, Coopers Plains Qld 4108
Phone: 07 3276 6062 (Aquatic Pathologist - submission enquiries)
Fax: 07 3216 6620

In northern Queensland, for complex cases or where input is required to prepare samples, contact the Aquatic Veterinary Officer in Townsville before sending samples:

Tropical and Aquatic Animal Health Laboratory
Department of Agriculture and Fisheries
18 Darter Street, Oonoonba Qld 4810
Phone: 07 4760 1592 or 07 4760 1510 (Aquatic Veterinary Officer - submission enquiries)
Fax: 07 4778 4307

Further information

Contact the Customer Service Centre.

Last updated 24 April 2015