ZIRC Health Services Sample/Specimen Preparation

Fish for Bacteriology and Necropsy Exam
Fish intended for bacteriology or necropsy exam should be shipped alive (see Shipping Instructions). Shipping containers for shipping live fish are available upon request. Bacteriology samples can also be taken from frozen specimens if necessary. We require notification prior to shipment of all live specimens to ensure appropriate personnel and lab supplies are available.
Histopathology Sample Preparation
For optimum results, fish must be alive and euthanatized just prior to fixation. Autolysis occurs rapidly once a fish dies. This makes fish that are found dead poor specimens for histopathology. Fish should be fixed prior to shipment using the protocol specified below.
Do not freeze fish.
Fixation Protocol for Histopathology Specimens

Prepare Dietrich's Fixative (100 ml) as follows. Store fixative at room temperature.
- 30 ml Ethanol (95%)
- 10 ml Formalin (Formaldehyde 37% solution containing 10-15% methanol, Sigma # F1635)
- 2 ml Glacial Acetic Acid
- 58 ml Distilled Water
Euthanatize fish with an overdose of MS-222 (tricaine methane sulfonate).
Carefully slit open the body cavity along the belly, trying not to disrupt internal organs.
The tail may be removed by cutting through the caudal peduncle well behind the anal fin. The tail should be left intact on fish with tail lesions and small fish
Use 10-15 ml of fixative per 1-2 fish in a sealable container. The volume of fixative should be at least 10 times the volume of the specimen.
Fish should be placed in a horizontal position with gentle agitation (e.g. laboratory rocker) for the first 24 hours of fixation. This will ensure optimal fixation and prevent artificial bending of the body axis.
Store and ship fixed fish in Dietrich's fixative. Fish can be stored for several weeks in Dietrich's fixative.