ABSTRACT
The majority of acid-base disturbances experienced in fish involve an acidosis, and consequently compensation for an acidosis will represent the main emphasis in this review. Regulation of intra- and extra-cellular pH is crucial to the normal functioning of all vertebrates, including fish. Acid-base status in fish can be influenced by a wide variety of conditions, including changes in the external environment, such as gas tensions, temperature, salinity and water pH, and internally induced challenges associated with processes such as feeding and exercise. The gills, intestine and kidney have all been implicated to some degree in acid-base regulation in fish, however, it is generally accepted that the gills are the dominant surface across which net acid-base transfer occurs. Traditionally, the gills have been thought to develop for gas exchange in embryonic and larval fishes to compensate for a reduction in total surface area to volume that occurs with growth.
