COMMON KOI SKIN DISEASE
Argulus - The Fish Louse
DESCRIPTION
It is said that this parasite can be commonly introduced into our koi ponds by frogs and toads. It is however easy to detect with the naked eye especially against the background of fins and white skin of affected koi. Size varies from between 1mm and 5mm. Attaching themselves to the koi by suckers which damages the skin, they also inject a poison into the body of the koi which causes inflammation, bleeding and potentially secondary bacterial infection. Pale green in colour, juveniles are more transparent.
Argulus must be eradicated quickly as the parasite causes considerable physical damage to the skin which often results in subsequent ulceration of the affected areas if left untreated.
TREATMENT
Chemical treatments recommended to eradicate these parasites are either Dimilin or Paradex. As the parasite is easy to spot with the naked eye, physical removal is suggested before chemical treatment to remove as many as possible from affected Koi.
Repeat treatments may be necessary to ensure that all generations of the parasite are killed.
Lernaea - Anchor Worm
DESCRIPTION
This parasites a common parasite on our koi which is clearly visible to the naked eye and can reach 10 to 12mm. The parasite burrows its head into the koi's tissue, under a scale and only the body and tail are normally visible.
If left on the koi, secondary bacterial infections can occur at the point of contact due to the damage caused by the anchors used to attach itself..
Lernaea lay eggs which can lay undetected in the pond and can hatch when conditions and water temperatures are right. Chemical treatments will not affect the viability of eggs so repeat treatments may be required to kill all generations.
Normally the parasite attaches itself by the dorsal or tail fin, and is also commonly found in large numbers on the bellies of koi when they are first netted from the mud ponds.
TREATMENT
Treatment is by manual removal of the parasite with tweezers under anaesthetic, ensuring that the whole parasite is removed. To be sure of complete removal, dip a cotton bud in strong potassium permanganate solution and dab the worm with this solution whereupon it will release its grip immediately. Pond treatments include Supaverm, Dimilin or Paradex
White Spot - Ichthyophthirius multifilis (Ich)
DESCRIPTION
White spot , one of the ciliates, showing the classic horseshoe shape macronucleus (above) is classed as a large protozoa, which can be detected by the naked eye on infected fish by the appearance of hundreds of tiny white spots where the parasite has bored through the skin of the host. The adult parasite drops off the host, surrounds itself with a capsule and fixes itself to a plant or rock. Inside the capsule the parasite divides and multiplies and eventually 250 - 1000 tiny 'swarmers' are released and these then swim off in search of a new host. The swarmers typically attack the dorsal and caudal fins of koi, although gills and body are also affected. The swarmers burrow through the surface of the skin and so the parasite resides in the body and not on the body of infected fish.
TREATMENT
Chemical treatments have to be long lasting and repeated several times to rid the fish population of these parasites. Recommended treatments are Acriflavine with salt , Malachite Green with salt, Malachite and Formalin, and prolonged use of salt at one half oz per gallon.
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