Probably the most common of the Parasites that invade our Koi are:-
GYRODACTYLUS (Skin fluke) and the DACTYLOGYRUS (Gill fluke)
Flukes cause Ulcer Disease. Other parasites can transmit and cause ulcerations,
but none so effectively as the pathogenic trematode, or FLUKE.
Assume that if you're treating bacterial infections, you also have concurrent infection with Flukes. The flukes are easy to diagnose with a microscope.
However, they are also easy to treat using Malachite Green and Formalin or Potassium permanganate is also excellent and used at the rate of 1.5
grams per ton (220 Gallons) - but it is even more important to ensure
good volumes of water changes after using this medication.
Chilodonella - this is the one parasite that kills so many fish so fast in the Springtime.
Chilodinella is one of the hottest fish killers there is. Under the scope
you may see a heartshaped organism, or a large round organism full of tiny bubbles. Alive, the Chilodinella resembles a heart shaped onion, with a fuzzy end where you could imagine the onions roots would be. These are actually cilia. Dead, Chilodinella are motionless round balls full of tiny bubbles. They may resemble Ich but they do not have a crescent nucleus nor do they move in their dead, rounded state.
Chilodinella clears EASILY with salt. Leave the salt in for 14 days, and be sure to supplement aeration, as gill damage d/t Chilodinella may be severe in the survivors. Chilodinella should be suspected anytime large numbers of fish are dying on the surface, or who roll over on their sides except when disturbed, the Koi dash madly.
Method of Erradication:
Treats easily with salt at the doseage rate of 3/4 ounce per gallon (0.75 percent).
Clears almost overnight, so immediate salting can save a lot of fish.
COSTIA: (Also known as Ichthyobodo Necatrix)
A High Magnification of up to 400 x must be used to see and identify this particular parasite which is one of the smallest of all the parasites, but one that can also, because of its size and can go undetected, play real havoc with your Koi and is most certainly a killer if undetected ..
Costia is responsible for a lot of the recent fish mortalities we've seen after Japanese style shows.
There are several reasons for this, which are worth discussion here.
- Costia resists drying. Empty tanks, nets, even dried nets and hoses, can transmit infective Costia from one group of fish to another. Folks are not very cautious about nets and bowls. A retail facility that does not rinse or disinfect their nets and bowls between tanks is capable of infecting every fish they sell, whether they originate in infected tanks or not.
- Costia is not always evenly distributed among fish populations or even upon an individual fish. What we are saying is that you may have a collection of fish in which only a small percentage of fish will have Costia. Numerous biopsies of some healthy looking fish are negative while the affected fish swarm with Costia. An immune capability is suspected among those fish that do not show morbidity under Costial attack. Secondly, the Costia may exist in small "patches" on skin and gill and be missed in routine scrapes. It is imperative that whenever you're biopsying a fish, you biopsy
general locations such as between the gill covers and the pectoral fins. But that you also biopsy any red or white patches upon the fish.
- Costia is easily missed under routine microscopy. There is an important reason why. For a definitive diagnosis, a microscope should be able to perform a competent 200X scanning power. 400X is sometimes important to diagnose Costia when numbers of organisms are low. Many of the new Chinese microscopes are labeled with 40X optics and 10X oculars but despite the listed caliber, are nevertheless poor at imaging at that power. So you often see nothing.
- Leaving the iris diaphragm open on your microscope defeats the necessary contrast to diagnose Costia. You should use the lowest power light and the smallest aperture on your iris diaphragm. For more on this, refer to the book or the web page for a diagram of these important microscope parts.
Please do not mess about with this particular parasite .. watch for the signs and do frequent scrapes using a good quality microscope at 400 x magnification.
Method of Eradication:
Initially you can try salt - this has been quite successful providing the strain of Costia infection you have is not immune to salt treatment .. treat at 0.5 percent (half ounce per gallon) and this rate of doseage can be increased to 0.75 percent.
Failing the Salt treatment and if Costial infection is still present, then Potassium Permangante as a dip is the only real solution to the problem .. at the rate of 1 gram per 5 ltrs of water for 3 minutes ..
You may need to retreat in the same manner for 3 consecutive days .. but please take another scrape and examine under the 400 x magnification prior to the additional dip treatments ..
This subject will be continued as time allows: