One Of The Biggest Culprits In Sick Pond Fish
Are Pond Water Organisms

These nasties, more commonly referred to as pond water parasites, are an all-too-frequent cause of Koi and pond fish problems, and very often death.

Parasites can become a big problem in garden ponds because a garden pond is NOT a natural environment, as a lake or river is. Fish in natural environments do have parasites, that’s a given fact. But they’re not stressed as the majority of garden pond fish are.

By stressed I mean the Koi or goldfish can be suffering from a combination of one or more of the following: poor diet; poor water quality; overcrowded conditions; and/or poor filtration. These “abnormal” conditions stress the fish. Their immune systems can’t fight off the parasites and then problems of one sort or another happen.

Think of it this way: as humans, if we get run down (not eating right; not getting enough sleep as examples) we are more prone to getting a cold, the flu ... or even worse.

Pond fish are the same. Poor environments = poor health.

Stressed Pond Fish Are At High Risk

Unfortunately, there are many different kinds of these disease producing organisms that can attack stressed fish. There are single and multi-celled types.

I have personally assisted Koi owners in identifying and then treating their sick fish.  In every case, overcrowding and very poor water quality (normally due to poor filtration equipment) led to the problems the fish were suffering: ulcers, fins that were starting to fray; listlessness; bulging eyes; a thick slime coat starting to develop; mouths with raw sores. You name it and I think I've seen it!

In my experience, the most “common” external parasites that adversely affect the backyard ponder’s fish are Costia, Ich (Ichthyophthirius Multifiliis), Fish Louse (Argulus) and two types of Flukes (Gill Fluke — Dactylogyridea and Skin Fluke — Gyrodactylidea).

This is not to say other organisms like Chilodonella or Lernaea (Anchor Worm) for two examples, don’t cause trouble, too. They do!

I am merely saying that from my own experience helping other worried fish owners, and from the training I have received in Koi health, the pond water organisms I named tend to be the most frequent offenders.

Internal parasites are obviously the most difficult to diagnosis, as well ... they’re inside the fish! I will not address these garden pond organisms here, as this article is trying to give you a good overview of the “usual” culprits.

Disclaimer: Please realize there are so many variables possible due to a fish's living conditions and pond water quality that “easy” diagnosis is not normally the case. Also note that almost all of these organisms are microscopic, thusly a skin scraping for microscopic examination is the only way to properly determine what is or isn’t attacking the pond fish. PROPER treatment is dependent upon proper diagnosis! The information provided on this web page is an overview only.

I will list these parasites and briefly mention the most common symptoms and conditions caused to garden pond Koi and goldfish:

Costia:  free-swimming, small protozoa that attack the skin and/or gills.

Symptoms: Early stage -- loss of appetite and general listlessness; fish may also be trying to rub their sides against the pond bottom or sides of the pond – this is referred to as flashing

Symptoms: As infestation progresses -- fish will most likely congregate under the waterfall, which is their attempt to get more oxygen; or you may see them gasping at the pond’s surface.

Ich:  one of the most common and wide-spread of all the pond fish organisms/parasites. Also known as “White Spot” because if the fish are heavily infested, it can look like salt or white grit was sprinkled all over them.

Symptoms: Early stage may cause a lot of “flashing” (as described above); even jumping up out of water; unfortunately death of fish often precludes the visual appearance of a severe infestation.

Fish Louse (or Fish Lice):  this is a somewhat easy one to spot with your eyes and in the early stages, too; a round parasite.

Symptoms: Most people notice what looks like a smallish patch of green algae on their fish. Taking a closer look they can see the round “louse”. There will most likely also be a red welt where this nasty has been sucking on the fish. Pond fish may look under-weight and red welts or even wounds will be evident. Severe infestations can infect the gills; respiratory distress will be evident.

Anchor Worm:  these can be evident to the naked eye -- they look like a grey or white thread coming out from under a scale(s)

Symptoms: flashing and/or jumping will be exhibited.

Gill & Skin Flukes:  **this is probably the #1 most commonly found parasite in the garden pond AND unfortunately one of the hardest to eradicate.**

Symptoms: Frayed fins; gasping at the pond’s surface; congregating under the water fall; flashing; jumping; sometimes there will be visible cloudy looking white lesions.

Take A Good Close Look At These Yucky
Garden Pond Organisms: Free Scary Movies!

Through the efforts of Duncan Griffiths, a Koi health teacher of mine (and one great guy too, may I add), you can see these stinkers in action. I encourage you to take a look at these nasty things as viewed under the microscope. Duncan has provided MPEG-1 movie clips and they’re all viewable with Windows Media Player.

These movies are on Duncan’s website, www.KoiQuest.co.uk. So, without further adieu, Click Here to see the scary movies.

To Summarize: Pond Water Organisms &
The Detrimental Effect Upon Koi And Goldfish

This brief overview of the most common parasites that can attack pond fish is my attempt to bring to your attention the fact that poor water quality and other poor fish-keeping habits will more than likely cause your fish to get stressed and then they’ll become vulnerable to parasites.

Don’t believe me? I can guarantee you that you will experience parasite problems at some point in time if you are lackadaisical in maintaining healthy water conditions for your pond pets!

In future articles, I will be explaining a bit more of each parasite and the suggested treatments.

Remember: Become a Knowledgeable "Water Keeper"
Not a "Sick Fish Fixer"

• Healthy Pond Water: Vital Need For Koi & Pond Fish
• Koi Fish Care Basics: Maintain A Healthy Koi Pond
• pH: Strive For Stability
• Ammonia: Toxicity Issues & How To Remedy High Levels
• Nitrite: Toxicity Issues & How To Remedy High Levels