Fish health ulcers and aeromonas and pseudomonas bacteria infections

Picture of ulcer on gold fish

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

Aeromonas bacteria or (more rarely) Pseudomonas bacteria almost always cause 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.

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

- 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.

- 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 ulcers often have ragged white margins bordered by a narrow zone of hemorrhage.

- Daily mortalities associated with this chronic form of 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) and he 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.