HETEROPOLARIA: External Protozoan Fish Disease

Here is a very interesting article for all Koi hobbyists and professionals.  Everyone who has ever dealt with Aeromonas (hole in the side disease) should read this article.

Heteropolaria affects the body, fins and gills of the fish.  This disease is often associated with Aeromonas and Pseudomonas.  Epistylis can be the cause for these two, and many other diseases. 

This disease is common in waters containing high organic matter, i.e. ponds and lakes.  It is prevalent during winter months, but outbreaks of red sore disease are more commonly seen in spring and summer months.

Heavy infections of Heteropolaria are characterized by white-gray cottonlike patches on the body surface.  Ulcers may develop, and the fish may roll on their sides and start "flashing" like they have parasites.  Red sore disease is also characterized by scale erosion, lesions on the body surface and bacterial hemorrhagic septicemia.  The infectious diseases are actually caused by the attachment of this protozoan.  See Fig. 1.1 below.

So basically, this protozoan may be the cause of secondary infections in your fish and must be dealt with accordingly.   Water quality is always the key, and infections like this may be prevented by maintaining good water quality.  Heteropolaria may be treated by using Formaldehyde or Forma-Green in the pond.   Metronidazole or Quinine Sulfate may also be used to combat this protozoan infection if you isolate the fish and treat him in a hospital tank.

If you use a nitrifying bacteria, like our Aqua Gold to maintain your water quality, heteropolaria and many other diseases may be avoided.  Earlier in this article we discussed the fact that heteropolaria is present in waters containing high amounts of organic matter.  Koi ponds contain enough organic matter to create a bacterial, fungal and protozoan "Factory" in most cases when not properly maintained.  This is why many people are "constantly" treating their pond month after month and never have any success with their fish.  The dirtier the pond, the larger breeding ground for disease is developed.  We know that summer months are especially difficult due to algal blooms and soaring temperatures.  Try to have some shade for your pond by planting some non-disciduous trees around it, or using a cover (many types of covers available through your local nursery).   Make sure you use plenty, even double or triple the amount of nitrifying bacteria in your pond during the summer months.  Also use an algal inhibitor like Crystal Blue if you have problem green water.  Also make sure your filtration is in accordance with the load of fish that you have in the pond.  Overfeeding is another cause of undue organic matter.  You don't need to feed your fish 3 times a day.  Once a day is just fine.  Feed enough food so that they can clean it up in about 5 minutes.   More than that is considered over-feeding.

Now, most importantly, we discussed the fact that heteropolaria can cause an opening for a secondary bacterial or fungal infection to happen right?  O.K.  so you have ulcerations on the fish.  I suggest first that you try something like Oxytetracycline Hydrochloride in the feed.  Use 2 teaspoons mixed in approximately 2oz. of water.  Mix well.  Add the medication to a spray bottle and spray it over 1 pound of koi pellets.  Let air dry (not in the sun, oven or with hair dryer), use a fan to expedite the drying process if necessary.  Once the food is completely dry, feed this to the fish once a day, for up to 14 days.  This treatment is for hemorrhagic septicemia which Koi are very susceptible to.  If the Oxytetracycline produces no results, you may have Pseudomonas.  If this is the case, use Neomycin or Kanamycin Sulfate Powder at the same directions and treatment method explained above.  With both diseases, isolate the fish if possible and use Forma-Green in the water to help prevent a secondary fungal infection like Saproglenia from developing.  A temperature bump also speeds up the healing process.  Bump it up to 75-80°F if possible.   We have cured fish with these diseases in two weeks using these methods.

If you do have fish with sores and are not sure which bacteria you are dealing with, it is suggested to use our Koi Fix© product which will kill both Aeromonas and Pseudomonas bacteria.

By: Dr. Gary Aukes; Pharm D, Dr. Brian Aukes; PhD., and the staff of National Fish Pharmaceuticals.