HAMES Laboratory Method:
Preparation, collection, and submission of tissues

Preparation, collection and submission of tilapia tissues for histopathology examination.

Preparation of fixative solutions:

• 10% Formalin
• Davidson Fixative

Purpose

On occasion, submission of selected abnormal tissues from tilapia may be need for histopathological examination. For the farmer familiar with the external and internal anatomy of tilapia, it is feasible to selectively sample tissue specimens, preserve these in appropriate tissue fixatives and send these samples to a diagnostic laboratory for evaluation.

Equipment and Supplies

1. Glass or polyethylene 100 to 1000 ml containers for tissue fixation.
2. Gloves
3. Dissection scissors and forceps
4. Tissue fixative (10% Formalin or Davidson Fixative)
5. Sealable, heavy plastic bags
6. Paper towels
7. Indelible marking pen or #2 pencil
8. Heavy cardboard box, tape and address labels

ALWAYS WEAR WATER PROOF GLOVES WHEN WORKING WITH TISSUE FIXATIVES

Collection and preservation of tissue samples

If the tilapia is to be sacrificed this should be done by exposure to an overdosage of anesthetic (see MS-222). Dissect and remove the organ tissue (s) of interest from the fish. Cut the tissues into pieces approximately 10 mm wide and 5 mm thick. Immediately place the tissues into the fixative solution. The volume of tissue to fixative solution should be in the range of 1 to 10. That is for every gram of tissue there should be 10 mls of fixative solution. Hold the tissues in the fixative solution for at least 48 hours before removal for transport to the laboratory. If Davidson Fixative is used preserve the tissues for 48 hours, remove and place into 50% ethanol solution for storage. Hold the tissues in the ethanol at least overnight before removal for transport to the laboratory.

ALWAYS WEAR WATER PROOF GLOVES WHEN WORKING WITH TISSUE FIXATIVES

Submission of preserved tissue samples

Once tissue specimens have been preserved, the samples can be removed from the fixative solution, wrapped in paper towels moisten with 50% ethanol, placed into at least three layers of heavy duty plastic bags, with each layer being sealed, placed into a box and mailed or transported to the diagnostic laboratory.