Fish Health Bacterial Ulcer Disease Aeromonas and Pseudomonas Bacteria

Koi ulcer disease has long being a scourge in the koi and gold fish industry.

Aeromonas bacteria or (more rarely) Pseudomonas bacteria almost always cause koi ulcer Disease and dropsy (pine cone disease). Bacterial infections, caused by members of the genus Aeromonas, are among the most common and troublesome diseases of fish raised in ponds and re-circulating systems.

Picture of bacterial ulcer on gold fish is shown below.

Whether acting alone or in mixed infections with other organisms, the motile aeromonads are responsible for significant financial losses annually through bacterial ulcer disease problems.

Aeromonads are capable of utilizing nutrients present in water and surviving for long periods in the absence of host fish.

They occur in the greatest numbers in organically rich waters, such as those found in ponds and other aquaculture systems which are thus prone to bacterial ulcer disease problems.

These bacteria can also be isolated from the skin and intestinal tracts of healthy fish, from pond mud, aquatic plants and certain protozoan parasites.

These bacterial ulcers often have ragged white margins bordered by a narrow zone of haemorrhage.

Daily mortalities associated with this chronic form of fish ulcer disease may be low, but can rise to high levels over time.

It should also be noted that the improper use of antibiotic feeds and injections has led to the emergence of aeromonad strains resistant various drugs.

It should also be noted that adding antibiotics directly to the pond water will kill the biofilter (now being called the bioconverter by some) and the beneficial bacteria in the pond.

Competition theory states that perfect competitors cannot coexist and that in order to coexist, species must utilise resources differently and have different competition abilities .... known as competitive exclusion.

Bacterial Ulcer treatment - A three-pronged koi disease attack based upon Ben Helm's advice.

Having isolated your Koi in a suitably sized and filtered quarantine system you should do following:

Add salt to the quarantine system. This will perform 2 useful roles.

a. Acts as a mild antiseptic that will help to keep the wound clean of pathogenic bacteria.

b. Reduces the amount of fluid that is lost directly through the open ulcer by reducing the osmotic gradient between the pond water and Koi tissue.

This will help reduce stress for the Koi.

Add a broad-spectrum anti-bacterial pond treatments such as acriflavine or malachite green to back up the salt in it's action against bacteria.

Apply a topical treatment directly on to the ulcer. This will involve anaesthetising your affected Koi, removing dead tissue and scales. Add a combination of a waterproof ointment on to the wound (Orabase) and an anti-bacterial topical treatment (concentrated malachite green). This will need to be replaced every other day or so, being careful not to disturb the healing wound. To support the Koi's healing, offer a good food and raise the water temperature to 20-25 degrees C and aerate vigorously.

Depending on the severity of the bacterial infection and how virulent the bacteria are, you may also be advised to seek a Vet's advice regarding the injection of a suitable antibiotic. This will also depend on the value and size of your Koi as a Vet's consultation and antibiotics are not inexpensive.

Ben Helm's Top 10 Fish Heath Koi Disease Prevention Tips

Regularly watch your Koi for changes in behaviour - an early indicator of disease.

Diagnose koi disease accurately, using specific diagnostic techniques (microscope etc)

Know your pond volume, and dose accurately.

Choose your pond fish disease treatment wisely. Is it tried and trusted? What is the recognised successful koi disease treatment programme?

Aerate when treating your Koi pond as DO drops during medications

Continue to monitor all Koi during disease treatment and respond to any acute behavioural changes during treatment.

Koi can become frisky during treatment. Prevent them from jumping out of your pond by covering it with a net.

So that Koi can heal themselves after you've treated the pathogen, support them with excellent water quality and nutrition

Turn off your UVc and by-pass your biofilter if recommended to do so by treatment directions.

Keep a diary of pond fish diseases and successful treatments - learn from your successes and mistakes.

Please also check out Ben's UK Pond Doctor site

Fish Health Bacterial Ulcer Disease Aeromonas and Pseudomonas Bacteria

Bacterial Ulcer treatment - A three-pronged koi disease attack based upon Ben Helm's advice.

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