Necropsy for diagnostic purposes is probably the most common; it aims to establish the cause of death or the nature of the morbidity of a fish or group of fish. In addition to the observation and record of the anatomo-pathological characteristics, the necropsy for diagnostics work will normally require sampling of fluids and /or tissues for subsequent analyses (haematology, histopathology, virology, bacteriology, parasitology, molecular genetics or immunology). A diagnosis is then issued after the critical analysis of the case history, clinical observations, anatomo-pathological findings and the laboratory results.
When the necropsy is performed within regulatory frameworks, along with international guidelines, additional procedures, the type and number of samples may be further governed by regional or national regulations. (e.g. European Union EU, or under “additional guarantees”), and procedures may also require validation and accreditation by external independent bodies (e.g. International Organization for Standardization ISO, The United Kingdom Accreditation Service UKAS).