Fish aquariums are popular in many households as they are great for people with allergies to other household pets such as cats and dogs. Caring for fish is a hobby for many, and can also cause calming effects and bring down anxiety in some. Just as people get sick, so do our pets. Fish can get sick too! We know bacteria grows in dry conditions, so let’s talk about some different infections that can inhibit your aquarium!

Bacterial Fin Rot

Poor water quality is the number one living condition that supports bacteria overgrowth and spread of disease. Prevention of Fin Rot is regular maintenance and monitoring the quality of water including pH, UV sterilization, and avoid over feeding your fish. Caused by gram-negative bacteria, these organisms degrade the fins of fish, “leaving them ragged and frayed. The damaged and frayed tissue is then vulnerable to secondary fungal infections” (Thomas Labs, p.1). Other symptoms include inflamed patches, discoloration of fins, loss of appetite and drowsiness.

Fish Tuberculosis

Certain fish such as Bettas are more likely to carry this disease or die from fish TB.  Symptoms of Fish TB include loss of color and scales, lesions on body, and curved spines. Treatment is very difficult and “curing fish is virtually impossible once the disease begins to manifest” (Aquatic Community, p.1). Euthanizing the fish in the infected tank is the suggested treatment because it is less painful for the fish instead of going through constant treatments that may never work and prevents the spread of this disease. Afterwards, the tank should be cleaned with bleach and left to air dry before replenishing your aquarium. All fish should be quarantined before introduction to any tank to avoid contamination of unknown diseases. 


V. Anguillarum is the gram-negative bacteria that causes this infection. It grows quickly and “is able to survive in sea water more than 50 months” ( This disease can affect both marine and fresh water fish and is transmitted through oral routes, external injuries or parasites, contaminated food with are all accomplished through contact between diseased and healthy fish. Symptoms may not be noticed when the infection spreads rapidly before the fish die. Noticeable symptoms include anorexia, abdominal distention, red spots on the body, swelling of internal organs and eye lesions. When fish are “reared in seawater net pens the disease is common resulting in high mortality if not treated with antibiotics. Several licensed vaccine preparations for aquaculture have been effective in the control of vibriosis” (ADFG, P.1).


Affecting both freshwater and marine fish, this disease does not cause significant mortalities, yet it causes unattractive wart-like growths (cysts) on the fish bodies, fins and gills which may reduce their worth. Lymphocystis is spread through contact with infected fish, but “does not appear to be spread by vertical transmission (i.e., from parents to offspring via infection of eggs or sperm)” (Yanong, p.1, 2018). Right now there is no quick treatment for this disease, but there is good news! Most cases resolve themselves in warm water fish after a few weeks, longer for cool/cold water fish, as long as the fish are in proper living conditions.

Aquarium Care

Maintenance of an aquarium can be easy if you closely monitor your water quality and keep a happy, lively tank. One beneficial tool is an Ultraviolet (UV) system to keep the aquarium water not only clear, but healthy, by inactivating any free-floating bacteria that enters the unit. Keep in mind, UV does not discriminate between good and bad bacteria, but overall your tank and fish will benefit from the cleanliness you can see and that your fish can feel!!

What Makes Aqua Ultraviolet different is

  • No Minimum Order Requirements
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  • Live Technical Support directly from our office.
  • We manufacture our patented products from our California location.
  • We directly handle warranty issues for you.
  • Unmatched filter performance.
  • Small and Large units for Ponds, Pool and Spa use, as well.
  • We offer unparalleled fresh drinking water products.
  • Installation videos and manuals are on our website.
  • Complete UV line, including a compact 400 Watt unit for larger installations.
  • All UV’s have a blue cap that indicates the lamp is operating.
  • We have the longest lamp life on the market, 14 months.

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Sources and further readings:
Fish Fin Rot Treatment, Symptoms, and Prevention

Aquaticcommunity –


Vibrosis, Diseases of Wild and Cultured Fishes in Alaska

Yanong, Roy – Lymphocystis Disease in Fish, 2018

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For over three decades, Aqua Ultraviolet has been the premier manufacturer of ultraviolet sterilizers and bio-mechanical filtration.

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