Parasitology and necropsy of fish.

Parasitic diseases are common in fish. Diagnosis can be made through gill biopsy, skin cytology, fecal examination, or necropsy. Common parasites include protozoa, helminths, and crustaceans. Determining the cause of death in a fish is important for maintaining the health of other fish in the same environment. Due to rapid autolysis, fish necropsies should be performed promptly after death. Samples should be preserved in 10% neutral buffered formalin. Squash preparations, tissue imprints, microbiology, and virology are also useful in obtaining a diagnosis.