A brief overview of nonneoplastic hepatic toxicity in fish.

Biochemical assays are not routinely used to assess liver damage in fish, therefore, a histopathological evaluation is usually required to determine the existence or extent of nonneoplastic liver toxicity. Many mammalian pathologists may be uncomfortable when requested to identify and interpret subtle liver changes in these unfamiliar animals. It may be reassuring to note that there are more similarities than differences between fish and mammals in terms of their macro- and microanatomy, physiological and biochemical characteristics, and pathologic responses to hepatotoxic substances. This brief overview addresses several topics pertaining to hepatotoxicity in fish, including: anatomic considerations, that is, how the anatomy of the fish liver may be predictive of its metabolic capacity, and also its microscopic appearance, following exposure to toxins; physiologic considerations, including comparisons between mammalian and fish livers regarding the uptake, elimination, toxification, or detoxification of xenobiotic compounds; morphologic responses to toxicity, in which some of the general types of findings that are most commonly observed in cases or studies of fish hepatotoxicity are highlighted; and last, responses of the fish liver to specific hepatotoxins.