Flukes |  Skin: Gyrodactylus and Gills: Dactylogyrus

  • Main symptoms: heavily affected fish with gyrodactylus often rub against the decor as they try to relieve the irritation. Fish with dactylogyrus have rapid gill movements and difficulty breathing. Be careful not to confuse these symptoms with those of ammonia/nitrite poisoning or due to lack of oxygen.
  • Secondary symptoms: weight loss and lethargy, overproduction of mucus (skin with milky apperance) or bleeding from the gills, fearful behaviour.
  • Direct causes : Gyrodactylus are invisible without a microscope (x100). Dactylogyrus are bigger (up to 2mm in length). The parasite is often present in very small numbers in healthy fish (no symptoms) but may start to proliferate due to stress, for example. Small fish and fry are especially vulnerable. As there are a number of other parasites that cause the same symptoms, the diagnosis can be confirmed after a sample has been examined under magnification.
  • Contributing factors: poor water quality, low immunity of the fish (various causes) .
  • Occurrence: uncommon in fish tanks but more common in ponds (Koi, goldfish).
  • Treatments : sometimes difficult. Start with a 15-minute bath in a 2.5% salt solution. A bath of potassium permanganate (more information on potassium permanganate here) is also possible. Malachite green is also relatively effective (more information on malachite green here). Warning: these examples will affect the filter of your aquarium. Few off-the-shelf treatments on the market: eSha gdex, Ntlabs Anti-Fluke & Wormer  (caution: the treatment kills invertebrates).

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Aquarium salt: the addition of aquarium salt in addition to a commercially available treatment. Recommended salt dosage for goldfish: 1 tablespoon per 15-20 liters (4-5 US gallons) speeds up the process of eliminating the parasites that cause flukes and adds electrolytes to reduce osmotic stress. Be careful not to overdose the salt in the aquarium: IT DOES NOT EVAPORATE (after a water change, only add the dose corresponding to the volume of water that has just been changed). Also be careful when using salt if you have other species of fish in the same tank: some species are intolerant to it. Aquarium salt can be found in pet shops, but any 100% natural non-iodised salt is suitable: do not use table salt! When the treatment is finished, partial water changes will allow the salt to be gradually eliminated.

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