Parasites in Koi ponds can often cause serious problems for the Koi, and hobbyist alike. By this I mean, that the Koi have the parasite problem, and the hobbyist has the problem of curing it! Knowing which parasite or parasites are present is essential for the correct remedy.
In order to be able to control levels of Koi parasites in ponds, it is necessary to understand something of their life cycles. Understanding how they reproduce, various life stages are, can allow us an opportunity to seriously reduce their numbers.
Low oxygen levels are more likely to prevail in summertime, when temperatures are higher, although some treatments for parasites can target algae and pond debris as part of the chemical reaction aimed at the parasites, and in so doing, create oxygen shortages.
It is wise to increase aeration in the pond before, during and after any medications are used. As fish consume approximately four times more oxygen after feeding, it is best that food is withheld for the duration of any treatment.
Simply overfeeding the fish can cause nitrite levels to rise above normal levels, or it can happen when the stocking level is in excess of that which the biological filter can cope with. Low oxygen levels and low KH frequently lead to nitrite levels rising. The whole pond system relies upon oxygen to function and adequate resources of calcium carbonate are essential to the bacterial activity of the filter.
Nitrate is the end product of the biological filter function and can be controlled by regular water changes. Test kits are available for measuring all the water parameters mentioned.
Frequent parasite problems would tend to suggest that the environmental factors within the pond are less than ideal. Fish living in a pond with good water parameters are able to cope with the small levels of parasites, which are often present in small numbers in perfectly healthy ponds.
Some keepers take the prophylactic approach: they rid the pond of any undue organic waste, and rid the Koi of as many parasites as possible in the late autumn when temperatures are still above 59*.
- Fish remains alone and ceases to be a sociable shoal fish.
- Fish jumping or scraping against pond side and floor.
- Fish refuses to feed.
- Fish breathes heavily, opening and closing of the mouth and gills.
If this is seen to happen, it is possible to treat an individual by way of a salt bath. Seawater contains about 3% salt. The bodies of freshwater parasites contain about 0.5% salt solution. Osmosis is a simple physics fact which guaranties that water will always tend to go towards an area of high salt concentration. In a salt bath of water of 3% solution, the parasites, being simpler creatures than the fish, can have the fluids withdrawn from their bodies by this difference in salt concentration. The same laws of osmosis exist for the fish so care and continuous observation of the fish during this treatment is essential. Once the fish begins to lie over on its side in a similar manner to that which occurs when a fish is anesthetized, it should be removed from this salt bath and placed into another container to recuperate. A maximum of two minutes is advised for this treatment which can be repeated if necessary a short time later.
An improvement in the disposition of a fish after this treatment can suggest that parasites may be the problem.
Let's look at some of the most common bugs..............
Argulus another crustacean parasite, round and up to 1cm wide. They have a sucker to hold on to the Koi with needle-like mouth parts which they stick into the Koi and inject a toxin. This causes intense irritation to the Koi and they scratch and jump and can cause bacterial infection. If they infect the gills they cause severe damage and often death.
Like other flatworms, Monogenea have no true body cavity (coelom). They have a simple digestive system consisting of a mouth opening with a muscular pharynx and an intestine with no terminal opening (anus). Generally, they also are hermaphroditic with functional reproductive organs of both sexes occurring in one individual. Most species are oviparous but a few are viviparous. Monogenea are Platyhelminthes and therefore are among the lowest invertebrates to possess three embryonic germ layers—endoderm, mesoderm, and ectoderm. In addition, they have a head region that contains concentrated sense organs and nervous tissue (brain). Treatment: Praziquantel as Prolonged immersion 10 g to each 100 gal.
Sudden swelling: A bacterial infection will cause internal bleeding. Slow swelling: Growing tumors, or even parasites, in the fish may cause it to swell. Slow swelling: Mycobacterium tuberculosis. Highly contagious! Bacterial dropsy is infectious so treat with an anti bacterial remedy and if possible isolate affected Koi.
Affected Koi often exhibit classic signs of irritation and flash, jump or rub themselves against objects in the pond in an attempt to rid themselves of their attackers. Flukes are not visible with the naked eye. When viewed under a microscope, the parasites are clearly visible as nearly transparent and worm like, and the hooks are clearly visible. Flukes are a bit like fleas on dogs and cats and it is common to see one or two on a slide as a healthy Koi can control parasite numbers and their mucus helps prevent the parasite moving. Treatment is therefore only necessary if flukes are seen in numbers.
Recommended treatment: Praziquantel follow up with BGDX
This virus is much less damaging than KHV and currently is very rare in the . SVC produces symptoms typical of those seen with many infections and can include dropsy, hemorrhages and/ or darkening of the skin.
SVC is classified as a "reportable" disease, so a confirmed diagnosis can lead to heavy handed federal government involvement.
Recommended treatments are Potassium Permanganate or ProForm-C. Follow up with BGDX
A severe outbreak of parasites requires treatment. However, in any disease outbreak it is essential to identify the prime cause. I hate to think how many Koi deaths have occurred because of repeated and unsuccessful treatments for parasites without knowing cause of them, which is usually an environmental factor.