Infection

In previous articles, we've seen that poor water quality/water composition and stress are causes of disease in ponds. A third important pathogen is contamination. Contamination means that one organism carries a pathogen and that this pathogen is transmitted to another organism. A significant number of pond fish diseases are transmissible. However, most forms of contamination can be prevented by taking the right measures.

Transmission of pathogens, such as parasites, bacteria and viruses can take place in different ways:

• Fish-to-fish transmission, caused by sick fish coming into contact with non-sick fish.
• Waterborne transmission, when contaminated water comes into contact with uncontaminated water
• Transmission via materials, when materials from contaminated water are used in uncontaminated water.
• Transmission via migratory animals, when animals move from contaminated water into uncontaminated water.

Don't panic

Now, we shouldn't overestimate the risk of infection and shouldn't react too panicked if, for example, a frog or a duck moves from one pond to another. A healthy fish in a healthy pond is usually perfectly capable of handling any hitchhiking parasites, thanks to its strong general resistance. It's utopian to think you can keep your pond parasite-free. Every pond, no matter how healthy, harbors some pathogens, which a healthy fish can generally resist quite well. It only becomes a problem when the fish weaken due to suboptimal conditions. This makes them more susceptible to a massive outbreak of the pathogen. In addition, there are some primary pathogens. These are pathogens that can easily infect a healthy organism, without causing any weakening. An example of this is the Koi Herpes Virus (KHV).

Preventive measures

So we must try to prevent an outbreak as much as possible. Don't tie the cat to the bacon. To minimize infection, the following preventive measures are recommended:

Keep the conditions in which the fish are kept as optimal as possible, to create a healthy population with a high general resistance.

• Prevent stress and damage to the fish, as this reduces their resistance.
• Quarantine new fish first. This is especially important to prevent an outbreak of primary pathogens in the pond. I will outline the quarantine procedure in a future article.
• Do not use equipment (nets, filter material, pumps, plants, etc.) in different ponds, or disinfect them first before using them in another pond.
• Make sure that no water from one pond flows into another.

( Click here for the article on Quarantine )

Author: Joop van Tol (Koitoday)