How to identify and deal with those nasty little unwanted guests !
The Macro parasites - Argulus, Lernaea, Gyrodactylus and Dactylogyrus.
The Protozoans - Trichodina, Costia, White Spot and Chilodonella<
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 Dimilin or Paradex
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.
Gill and Skin flukes are two of the family of monogenetic trematode genera, all of which are characterised by the large grappling hooks which are used to attach themselves to their victims.
Flukes are another common parasite affecting our koi are are both egg layers and live bearers. They range from 0.05 to 3.00mm long and there are actually a huge number of species in the genus
Affected koi often exhibit classic signs of irritation and flash or rub themselves against objects in the pond in an attempt to rid themselves of their attackers.
Koi suffering from infestations of gill flukes may suffer respiratory problems as the flukes begin to damage the delicate gill tissues. Secondary bacterial infection often occurs in koi left suffering from these parasites, due to the physical damage caused by the anchors.
Chemical control of both types of fluke can be achieved with Chloramine T, Malachite Green Formalin and Masoten, or Potassium Permanganate. In order to kill all generations, repeat treatments may be necessary, the frequency being dependent on temperature and chemical used.
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.
Chemical treatments recommended to eradicate these parasites are either Masoten, Dimilin or Paradex.
Repeat treatments may be necessary to ensure that all generations of the parasite are killed.
Once dead, the host is quickly deserted by the parasites who swim off in search of new prey.
Affected koi may show classic signs of flashing and rubbing, may hold their fins clamped against their body and appear listless. They will also hang at the pond surface and gasp for air in severe infestations.
Recommended treatments include Malachite Green and Formalin, Potassium Permanganate or Salt baths at 3% ( 4 and one half oz. per gallon )
Chilodonella is classed as the most dangerous of the Protozoan parasites and can cause mass fatalities especially in overstocked ponds and aquaria.
It is between 40-60 microns in diameter and can be easily identified on a microscope slide using 100 x magnification.
It reproduces itself by transverse fission, and the adult has a heart shape appearance, although this is changeable, and its body is evenly covered with cilia.
The parasite can actively swim short distances so healthy fish are easily infected. An infestation of Chilodonella can cause opaqueness of the skin, especially between the head and dorsal fin and in severe cases the skin can look swollen. Gills are also attacked and can be totally destroyed, quickly killing the host.
Costia is a minute Flagellate with 3-4 flagella. It affects both the skin and gills of koi, and reproduces itself by binary fission. Infestations of this parasite can appear very rapidly indeed, and koi suffering infestations exhibit the classic symptoms of lethargy, clamped fins, rubbing and flashing and the skin can take on a grey white opaqueness.
Costia normally only affects fish that have already been debilitated by some other cause, and can often be seen on koi as a secondary parasite.
A high magnification must be used to view these parasites (300 x) and staining is recommended for positive identification.
Costia is classed as a cold water parasite and is not normally able to survive temperatures in excess of 85 deg F.
Recommended treatments include Potassium Permanganate, Acraflavine and strong salt baths of 3% ( 4 and one half oz. per gallon )
A magnification of 100 to 200 x is required to view this parasite.
Recommended treatments are Potassium Permanganate
Trichodina is one of the easiest protozoan parasites to detect under the microscope as it is almost perfectly round with hundreds of hooks which resemble cilia found its periphery and it constantly rotates as it moves through the mucus, causing tissues damage.
It attacks both skin and gill tissues of our koi, and can often cause more damage to gills than realised.
Classed as a warm water parasite, it can survive for some time without a host. It causes vegetation of the skin giving rise to a grey white opaque appearance on the body of infected koi which exhibit the classic symptoms of flashing, rubbing and lethargy.
Ichthyophthirius multifilis (Ich) - 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.
White spot on microscope slide
The complex nature of the life cycle of white spot can render it difficult to treat as it is only the free swimming swarmers that can be killed with chemical treatments. Once the swarmers attach themselves to our koi, until they detach as adult parasites can take between 4 days at 27 deg C (80 deg F) and up to 4 to 5 weeks at 10 deg C (50 deg F). The parasite becomes encapsulated in only one hour after leaving the host. Newly produced swarmers can however only live without a host for up to 55 hours maximum, so by simply removing koi from a pond for three days, it can be cleared of the parasite completely.
Chemical treatments have to be long lasting and repeated several times to rid the fish population of these parasites. Recommended treatments are Acraflavine, Malachite Green and Formalin, and prolonged use of salt at one half oz per gallon.
Chemical treatments should be repeated at least twice to ensure complete eradication.
