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.
Gills swollen and pale
High mucus secretion
Swimming with high speed
Use anti Flukes medicines according to the tank size (Dosage 10 ml per 100 liters)
As flukes are often the root of ulcers and other secondary infections, treat for flukes before treating with antibacterial or antifungal medications. A number of treatments are available for flukes, those containing Praziquantel are the most effective.