Carp Parasites, stocking carp the risks

Carp Parasites, What follows is important advise for anyone looking to stock their carp lake.

A dead 50+ carp

To stock a fishery with carp can be a rather costly affair. You can stock your lake with small fish which can take years to grow to a fair size or you could choose to stock with larger carp. If you choose the latter then be prepared to pay alot of money. A 20lb fish for example can cost several hundred pounds. The single biggest risk in UK fisheries today is the introduction of disease from new stockings and the catastrophic effects of illegal and foreign fish introduction into existing ecosystems. This has led to large numbers of fish fatalities at a variety of venues the length and breadth of the country. As a consequence of this, a balanced fishery with a healthy stock of growing carp is an extremely valuable asset and the highest priority must be given to the welfare of the original fish.

Carp parasites to check for...


Choosing a reliable and reputable fish supplier is critical. On introduction to your venue the carp need to be rigorously checked, the time spent checking the fish is time well spent. Key areas to check are the flanks , around the fins and under the gill plates. The gills should be a nice deep red colour and the plate edges should be feathered. All possible measures should be taken to preserve existing fish stocks before re-stocking with new fish. A fish biologist should be present at any new stocking with all the necessary equipment, microscopes etc.. While this may initially be costly, it will help to preserve your valuable carp.


Carp Parasites Pictures

Trichodina is the easiest parasites to view under the microscope. It is almost perfectly round with hundreds of hooks. Moving in a spinning top motion. The Trichodina causes damage to the gills. Carp with this parasite will often be unusually pale in appearance. Carp infected with Trichodina will show signs of distress including flashing, jumping and rubbing as well as lethargy. Under the microscope a magnification of 100 to 200 x is required to view this parasite.

Argulas(fish lice)

A common parasite which can weaken fish though rarely causing death. These pests are visible to the human eye, they look like a transparent oval object around 5mm in size with a black spot in the centre. Usually visible to the human eye on the flanks and around the pectoral fins. These parasites are irritating for the carp causing them to flash, jump and rub against objects in an effort to rid themselves of the pests. Over time Argulas will weaken the carp's immune system leaving then vulnerable to infection.

Gill and Skin flukes

Flukes are another common parasite found on carp. ranging from 0.05 to 3.00mm long and resembling a small worm. Unlike argulas, gill flukes are not visible to the human eye. Clearly visible under a microscope they resemble a long worm with large hooks on the end which they use to attach themselves to their victims. As with Argulas, carp with gill flukes will exhibit signs of flashing. Gill flukes are a bit like fleas on cats and dogs, more of an irritation than a danger.

Anchor Worm

Anchor worm is clearly visible to the naked eye and can reach 10 to 12mm. This parasite burrows its head into the carp's tissue, under a scale and only the body and tail are normally visible. The female buries into the skin and underlying tissue to hold on. The damage this causes can start a bacterial infection which can then spread. Parasite removal is by physically removing with tweezers.

Gill maggots

Gill maggots are several millimetres long and grey or grey/white in colour. If left untreated heavy infestation will cause sever damage to the gill plates allowing secondary infections to develop and eventual deaths from oxygen starvation.

Bacterial diseases : Cotton Wool Disease | Dropsy or Pine-cone Disease | Finrot and Ulcers

Fungal infections : Saprolegnia Fungus


The parasites listed as well as the fungal and bacterial infections, effect not only fresh water common and mirror carp but also the Koi Carp. Most study on these pests has been carried out in this sector. The suggested cures and medicines relate to Koi carp, but are the same for all carp varieties. The doses advised are for garden ponds which may hold a few hundred to thousands of gallons. Carp lakes will usually hold millions of gallons. This means the cost to the average carp lake owner will be substantial. Avoiding parasite introduction is the best measure. If your carp are infected with parasites and you require help, you will need to contact an expert. Van Der Cruyssen is Dutch but speaks excellent English. Her knowledge on this subject is second to none.