Notes

1. Examine the fish externally.
2. Take a skin scraping. The skin must be moist, not dried out in order to get protozoa. Put on a slide with water and a cover slip and observe under the dissecting microscope.
3. Put a small snipping of the tail fin on a slide. May see parasites better with this entire section.
4. Blood smear - snip tail off, get blood from caudal sinus.
   -- remove blood from gills, especially to see trypanosomes.
5. Remove operculum, then remove gill arch by cutting some of the filaments. Observe grossly, then fix in Bouins or 10% formalin. Bouins is good because it decalcifies the bone.
6. Examine inside the mouth. Copepods can be seen inside the mouth and on the gills. Do a squash preparation of the gills for sporozoans.
7. Open body wall laterally and ventrally and remove flap.
8. Take a sterile culture of the kidneys for Columnaris. Flame a bacteriology loop, plunge it into the kidney and streak it onto the appropriate medium. Incubate at various temperatures. Fish pathogens tend to be gram negative and oxidase positive.
9. Malnutrition, amino acid deficiencies cause pale, white fatty livers.
10. Gastrointestinal parasites - Nematodes tend to be in the caudal portion of the intestinal tract.
    -- Acanthocephalans.
11. Sporozoans are everywhere in fish. Histopathology must often be done to detect them.
12. Take some sections through the entire fish to detect plerocercoids in muscle.
13. Remove the brain.

If no answers can be found, do bacterial and viral cultures. If the fish is small, do serial histopathological sectioning.

Skin testing for tuberculosis may in future be possible since fish may have the ability to mount an immediate hypersensitivity response.

N.B. A present theory for fraying of the fin is that the blood pressure and flow in the tail are so low that if there are any toxic problems, the fin frays due to ischemia.