There are many different types of pond fish parasites, each with its own method for invading your pond and making your fish sick. Parasites are aggravating, but they are a normal part of operating a pond, so you’ll need to know as much as possible about them when you set up your pond.
There are two types of parasites in ponds, internal and external. Most of the parasites your fish will be fighting off are external, but there may be occasional infestations from internal parasites. Healthy fish in healthy ponds will be able to fight off most parasitical problems relatively well, but there may be times when you will have to intervene to save your fish. Wild fish generally have more room in which to swim about so they rarely have direct contact with others who may be infected with parasites. When in a captive pond, it is normal for fish to have a heightened amount of contact with other fish and that is when transfer becomes a problem.
Fish normally are covered with a layer of slime on top of their skin (or scales, depends on how you want to say it). That slime is a necessary part of the health of your fish. It prevents a fish from contracting many illnesses. When a fish becomes stressed or is in a situation which is not ideal, its coating may become compromised. When that happens, it is like an open door for pond fish parasites to invade the system of that fish, but there are a select few parasites which can sicken a fish which does have the healthy layer of slime. The bigger threat to most parasites is from an infection which may come about once the fish’s immune system has been damaged because they will not be strong enough to fight that infection off.
Pond fish parasites will cause several symptoms in fish which you will be able to notice on your own. You will want to look for changes to the skin, eyes, fins, any growths or lesions on the fish, redness, any inflamed areas, ulcers and odd behaviors such as wagging, rubbing against the sides of the pond or any other items in the pond, lethargy, or constantly floating at the surface of the pond. Other problems will be microscopic, but whenever you treat your pond for something, you will want to take a sample for testing first to guarantee exactly what the problem is before you treat. If you do treat one problem, there is likely to be another in the pond which you may miss without careful testing and diagnosis. Make sure you seek the help of professionals if the problem is something you cannot handle on your own.
Making sure you are well educated in fish illnesses will help you should your pond ever become infected with pond fish parasites.
