Mycobacterial Infections of Fish

ticularly in intensive aquaculture systems and display aquaria. These diseases are collectively referred to as “atypical mycobacteriosis” or simply “mycobacteriosis.” The term “fish tuberculosis” has been used in the past to refer to this group of diseases, but the term is not appropriate and should not be used. Tuberculosis is a very important disease of humans and mammals, but fish do not get tuberculosis. All fish are susceptible to mycobacteriosis, though some species seem to be at greater risk than others. The disease has been reported in a broad range of fish species from freshwater, marine and brackish water environments. In freshwater systems, the centrarchids, especially striped bass and their hybrids, seem especially susceptible. In mariculture, mycobacteriosis has been reported in sea bass, turbot, Florida pompano and others. In marine aquaria, the sygnathids (members of the sea horse family) are notoriously susceptible. Mycobacteriosis was formerly a problem in the salmon industry, but since the feeding of fresh fish offal (waste products from slaughtered fish) was discontinued and modern processed diets were developed, the problem has largely disappeared. The susceptibility of aquarium fish may be related, at least in part, to their longevity. Fish in the families Anabantidae (bettas and gouramis), Characidae (tetras), Cyprinidae (barbs, danios, koi and goldfish), and some members of the Cichlidae (including freshwater angelfish) may be more prone to the infection. This disease is also of concern in recirculating systems and once established can be difficult to eradicate. High organic loads, water quality characteristics common in intensive systems, and very crowded populations can all exacerbate the infection. Mycobacteriosis is an