Many types of bacteria can infect multiple organs of a fish

Fig. S2 Phylogenetic tree of all representative fish gut bacterial sequences used in the study.
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Bacteria Bloom
Bacteria Bloom (cloudy water) will occur 2 to 4 days after fish are added to the tank. The cloudiness, caused by initial bacteria growth, is not harmful to tank inhabitants, and will clear on its own. Have patience! If your water does not clear after 10 days, consult with your Aquarium Adventure Fish Specialist.
, a ,  bacteria caused losses in farmed marine and freshwater finfish of US$100 million in 1997.
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We also wished to evaluate these fish gut bacterial communities within the broader context of host-associated and free-living bacterial communities. To do this, we added these samples to a previously described data set that included 99 801 nonredundant 16S rRNA sequences from 464 samples compiled from 181 published studies (). This data set included diverse free-living (e.g. freshwater, saltwater, soils, etc.) and host-associated (e.g. mammals, insects, etc.) bacterial assemblages (Broad Dataset). The parsimony insertion tool in ARB was used to build a phylogenetic tree (), providing us with a much faster and more feasible means for phylogenetic analysis than that used for our other data sets. Unweighted UniFrac distances were used for the PCoA. The classification of some important groups of bacteria involved in fish and shrimp spoilage was studied.
Photo provided by FlickrCounty public health investigators said the likely source of a woman’s bacterial infection is fish bought from a Bellevue supermarket.
Photo provided by FlickrFlavobacteria are found in both fresh- and salt-water environments and cause significant problems in fish farming worldwide.
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Known as "New Tank Syndrome" these fish are poisoned by high levels of ammonia (NH3) that is produced by the bacterial mineralization of fish wastes, excess food, and the decomposition of animal and plant tissues. Additional ammonia is excreted directly into the water by the fish themselves. The effects of ammonia poisoning in fish are well documented. These effects include: extensive damage to tissues, especially the gills and kidney; physiological imbalances; impaired growth; decreased resistance to disease, and; death.Nitrosonas bacteria are traditionally held as the bacteria that are responsible for converting ammonia into compounds called nitrites. The establishment of a healthy reproducing colony of these bacteria takes about 2-3 weeks. Once created in the filter media, these bacteria will instantly change all ammonia present in the water into nitrites. Nitrites, though, are fairly hazardous compounds to fish health as well, so the filter must employ the use of another group of bacteria to adequately filter the water. Nitrobacter or Nitrospira bacteria are held accountable for the conversion of nitrites to nitrates. These bacteria behave in a similar fashion to the Nitrosomonas bacteria in that they will consume nitrites and excrete nitrates as a waste product. Two weeks are generally necessary for these bacteria to fully seat themselves into a filter’s media. Again, once established, these bacteria will instantly change (through an oxidation process) all nitrites present into nitrates.Understanding the Nitrogen Cycle
Biological filtration is by far the most important for keeping fish in an aquarium. From the moment fish are introduced into the aquarium, they begin releasing ammonia, their principle waste. If allowed to build, this ammonia can kill fish by burning the gill tissues and preventing them from taking oxygen. Beneficial aerobic (oxygen-loving) bacteria help us filter the water through biological filtration. Essentially, waste laden water passes over bacteria, which consume the waste and convert it into less toxic compounds.It is critical to remember that the media involved house billions of living bacteria, and the presence of these bacteria is what keeps your fish healthy and thus the absence of these bacteria can result in the loss of all other living organisms in the aquarium. When it becomes necessary to clean the filter media, usage of the aquarium water to rinse the media is essential. If the media is instead rinsed with chlorinated tap water, these important bacteria will be killed and the fish’s toxic waste will not be removed. Ideally, the rest of the tank is left untouched when cleaning biological media, for it too houses bacteria, and they will help pick up the slack when the main component of bacteria are under stress from cleaning.