Bacteria from Fish and Other Aquatic Animals - Survival-training.info

Introduction
This manual attempts to provide a source that enables the identification of bacteria that may be found
in animals that inhabit the aquatic environment. The emphasis is on bacteria from farmed aquatic
animals. In the words of Louis Pasteur, ‘chance favours the prepared mind’; therefore, an informed
microbiologist will have a better chance of identifying those bacteria.
Our knowledge about the isolation and identification of bacteria from aquatic animals and the
aquatic environment is expanding at a rapid rate. New organisms, be they pathogens, environmental,
normal flora or potential probiotics, are being described and reported each month. This has happened
due to an increase in aquaculture research, an increase in intensive fish farming systems, an increase in
the international trade of live aquatic animals and products, and the emergence of new diseases. More
and more laboratories are becoming involved in the isolation and identification of these bacteria in
either a diagnostic or research capacity. In this manual there is an emphasis on bacteria of interest to the
aquaculture industry either as pathogens, normal flora or strains that may be used as probiotics. Some
bacteria that have been isolated from diverse habitats are also included. This manual attempts to provide
these laboratories with an up-to-date and standardized database of methods and biochemical identification
tables that can be used to isolate and identify bacteria from aquatic sources. Molecular diagnostics is
becoming more routine in many laboratories and a section on molecular identification of bacteria using
the PCR and 16S rDNA sequencing is also included in this manual.
Many laboratories receive samples not only from veterinary sources, but also samples from zoo
animals such as penguins, seals, seabirds, and aquatic mammals both captive and wild. From other
aquatic sources, samples for analysis may come from fish, both wild and cultured, freshwater and
marine, aquarium fish, tropical fish, and cultured aquatic animals such as abalone, pearl oysters,
seahorses, lobster, crayfish, yabbies, marron and prawns. All these hosts have their own microflora and
potential bacterial pathogens and are found in a diverse range of habitats from tropical to cool temperate
climates. This manual includes as many of those bacteria as possible that may be found during examination
of samples from this diverse range of host and habitat. Not only pathogens, but also environmental
and saprophytic organisms, are included to aid in the understanding of the microflora that may be found
in such samples. Many bacteria from the more extreme environments have also been included as, with
the increase in aquaculture throughout the world, and the increasing knowledge about the microflora of
such habitats, these organisms may find their way into some laboratories via the samples submitted.
Therefore, those isolates that are capable of growing on the isolation media recommended for aquatic
organisms such as ZoBell’s or Marine agar 2216 (Difco) are included in this manual. In addition, I have
included some of the Antarctic organisms that have been suggested as a low-cost food source for some
marine finfish because they are rich in omega-3 polyunsaturated fatty acids significant in the diet (Nicols
et al., 1996) and thus they may be cultured from samples that come into a laboratory.
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