Why Vaccinate Your Koi & Goldfish?

by John Howell


  • To help prevent disease
  • To reduce or eliminate the need for antibiotics
  • To reduce the chances of Aeromonas becoming more resistant to antibiotics
  • To reduce the chances of scarring, deformity, & death of valuable fish
  • To assist your fish to mount an immune response during times of stress including: water temperature fluctuations in Spring & Fall, poor water quality, when biofilter is overloaded or undersized, when new fish are introduced that may be carriers, when parasites are present, when cross contamination at shows may occur, and during seasons when the immune system is not fully active



The Aquaculture Industry has been successfully vaccinating for years at a lower expense & higher success than was possible under antibiotic & post disease treatment only. The deadly outbreak in Japan last year has finally brought the recognition of vaccines to the Koi & Goldfish Industry.


Ulcer disease or hole-in-the-side is caused by a bacteria known as Aeromonas salmonicida. A contagious and deadly disease, it can only be treated with the newest antibiotics. Aeromonas has long been a curse to the Koi & Goldfish hobby. An even more serious threat is a new strain of Aeromonas which came out of Japan last year. Often referred to as the “new disease”, it is actually an incredibly fast killing strain of Aeromonas identified as Aeromonas hydrophilia. To understand the seriousness of this strain, here is an excerpt from a “Disease Alert” sent to Aqua Health dealers this past February.


This disease may or may not manifest itself like true hole-in-the-side. In many situations it goes septicemic before any ulcers are displayed. The fish just quickly die before treatment may be initiated or if treatment is begun, the treatment may prove to be ineffective and the fish die in the same short order. We are not talking individuals here, rather we are talking entire populations or a high percentage (>65%) of a given population. … In addition, as the water temperature warms up, this bacteria manifests extreme virulence and rapidity of action. The Japanese have traditionally isolated symptomatic individuals, warmed the water to >74F, added salt and antibiotics and saw healing within a few days. When that method is now used, reports are that 100% of the treated fish are dead within 72 hours! …. very significant losses are occurring. … the Japanese are extremely concerned about losing their livelihood due to this problem…


When, What, How & Why of Vaccines:


  • Vaccines help the fish develop a strong immune memory response against specific infections
  • Vaccines have shown to be 99% effective in preventing disease
  • Infected fish should first be separated & not returned to the population until clear of disease signs & properly vaccinated
  • All fish not exhibiting signs of disease should be vaccinated & no new fish should be introduced unless properly vaccinated and quarantined
  • Vaccination requires 400C days before effectiveness is realized (ex. daily temp = 20C, 400C/20C=20 days)
  • Fish that previously recovered from disease may be carriers. Vaccination will either cause the carrier fish to break with symptoms or be considered clear at the end of the 400C days wait
  • Fish CAN NOT contract the disease from the vaccine because it uses only formalin inactivated bacteria – Injectable vaccine provides 12 month protection
  • Immersion vaccine recommended for use on fish less than 10g ea. Initially it requires 2 treatments, with the second 2 to 4 weeks after first. Follow up is single treatment every 6 months