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Aeromonas Alley

Aeromonas Alley

Aeromonas Alley, just hearing those two words can make a koi-keeper’s skin crawl. As koi hobbyists we know that spring is a stressful time for our koi. Springtime is a period when our koi fish are naturally weak and immunologically stressed after the long winter and fasting period. When pond water temperature is at 42-62⁰F Aeromonas bacterium can run rampant. Unfortunately, it is in this temperature range when our koi’s systems are just starting to wake up leaving them highly susceptible to parasite and bacterial attack. And, as if that weren’t bad enough this is also the time when our pond bio-filters are slow to mature.

Aeromonas lives in our koi ponds and alongside our koi at all times. It is part of a normal pond environment. Aeromonas is an opportunistic pathogen that does very well in cool, organically-rich water. Any decaying matter and fish waste will feed it and encourage its growth. In fact Aeromonas (and Psudomonas) can even be found on a koi’s body as well as internally, in the koi’s intestines. Koi can never escape from it. Many bacterial infections are caused by Aeromonas and Psudomonas including ulcers, mouth rot, fin rot and more.

Steps to control Aeromonas

As koi keepers we must do our best to keep Aeromonas and Psudomonas at bay. Heat is one of the best defenses against Aeromonas. The koi immune system will be just 50% effective in 65⁰F water. Unfortunately, most outdoor ponds do not have any form of mechanized heating and must rely on the sun for warmth.

One thing that you do have control over is waste in the pond water. Keeping your pond clean is paramount in controlling Aeromonas. A pond with minimal decaying matter and fish feces discourages high counts of the deadly bacterium.

Another thing we suggest is the use of Aqua MedZyme. The Aqua Medzyme product is not a medication or an antibiotic; it is a blend of natural microbes, micro nutrients, probiotics and enzymes. The ‘good bacteria’ in it consumes the same food that Aeromonas and Psudomonas survive on. It starves them until their numbers are so low they no longer pose a threat to koi. The dry Aqua MedZyme product can be administered at temperatures as low as 40⁰. Aqua MedZyme is a 100% natural pond bacteria.

Bio-filters are slow to start working in the spring of the year. But, one particular ceramic filter media is quick to colonize with beneficial nitrifying bacteria. It is the authentic Bacteria House filter media. This media provides an enormous amount of space for good bacteria to adhere, reproduce and set to work purify the pond water.

To purchase Aqua MedZyme visit our website:

Read more about Bacteria House filter media here:

Read more about Aeromonas and Psudomonas here: