Gill flukes or Dactylogyrus are parasites, which particularly lodge in the gills of koi. A gill worm consequently is a very dangerous parasite, which will not become larger than 0.1 to 0.3 mm. The appearance of a gill fluke is that of a skin worm or Gyrodactylus. This is why they are closely related to each other. However, a skin worm is larger (0.3 to 0.5 mm) and it is viviparous. A gill fluke lays eggs. Both the gill and the skin worm come under the group of Trematodes.
Gill flukes are specific for fish species. A gill fluke, which lives for example on koi, do badly on sturgeon. Yet it is possible that gill flukes will hold out for a while on different fish species. Especially if there is lack of species-specific hosts. However, this will not easily result in a plague.
Gill flukes are usually brought along by newly introduced fish or by birds, drinking from the water. Gill flukes can be easily recognized by the worm part, which is projecting from a fish.
Treat and prevent gill flukes
As a reaction to infection with gill worms fish will make additional mucous, which may have a suffocating effect. The symptoms of infection by gill worms include keeping one gill shut, accelerated breathing, shaking the head, swimming backwards and rubbing gills.
Gill worms can be treated properly with anti worm means. A double treatment is to be recommended, because the eggs of the worm cannot be treated with medicine. If the eggs will hatch, the second treatment should be performed. Of course it is always better to prevent Gill worms.
It is important then to feed your fish during the summer months on a quality feed. Feed, containing a large amount of all important nutrients, vitamins and minerals. In this way fish will have enough resistance after winter. Different causes can be bad water quality or, as the case may, too many fish in the pond. The directive is 50 cm of fish length per 1,000 litres of water. A properly functioning filter, provided with activated carbon will bring relief, because this carbon can purify water from various micro dust particles. Also different pathogenic organisms will be filtered with it.