Velvet disease
The velvet disease (also called oodinium infestation , Oodinose , coral fish disease and Pillulariskrankheit and Colisa's disease ) is a by dinoflagellates pillulare Piscinoodinium (first in 1951 by Wilhelm Schäper Claus as the causative agent of the disease in Colisa lalia observed) and Amyloodinium ocellatum and Oodinium cyprinodontum caused parasitosis in Fish that attack the skin and gills. If you look at infested fish lengthways from the front at an angle towards the light, the skin appears cloudy and as if sprinkled with powdered sugar. If the infestation is more severe, the skin appears velvety, from which the well-known name velvet disease is derived. This coating has a yellowish to brownish color.
Occurrence
Piscinoodinium pillulare occurs only in freshwater fish in warm and cold water areas. In marine species, Amyloodinium ocellatum and Oodinium cyprinidontum are considered to be the cause of the disease. Infection occurs mainly through newcomers, as the parasite is not viable for a longer period of more than 24 hours without a suitable host.
Course of disease
In contrast to its marine representative Amyloodinium ocellatum , Piscinoodinium pillulare does not feed on the cell components of its host, but has photosynthetic abilities due to the chloroplasts in its cells . The skin is nevertheless massively damaged and dissolved by the root-like plasma threads. Inflammation or fungal infections are also less common. In the initial stage, the gills are affected, where the parasite spreads and causes severe shortness of breath in the fish. The fish skin can appear completely free of the parasite, and only when the cyst has been left does P. pillulare spread crawling over the entire skin surface.
The course of the disease is chronic over several weeks and difficult to detect even in a smear, as the parasite can hardly be distinguished from mucous membrane cells. In the further course, the massive spread of the parasite leads to the destruction of the cell network, with tissue death, up to shredded detachment of the skin and bleeding within the gill leaves. If left untreated, the disease is always fatal for the fish and is associated with a long disease.
Symptoms that occur before a visible infestation:
- increased or accelerated breathing (identical symptom in ichthyophthiriosis )
- splayed gill covers
- Fish rub against the floor and objects (identical symptom in ichthyophthiriosis)
- Refusal to feed, emaciation (identical symptom in ichthyophthiriosis)
- unnatural discharge (identical symptom in ichthyophthiriosis)
Symptoms that occur when the infestation is visible:
- violent breathing frequency (identical symptom in ichthyophthiriosis)
- slimy gills
- Fin clamps with rubbing movements (identical symptom in ichthyophthiriosis)
- Fish stay near the surface of the water
- Fish stand near the movement of water
- velvety, powdered sugar-like topping
- Threads of mucus hang from the gills, skin peels off
treatment
The development and life cycle of P. pillulare is strongly dependent on temperature. In colder pond water, the development takes longer than in warm water fish and temperatures of 25 ° C and above. If the temperature for treatment is increased in order to accelerate the life cycle of the parasite, there is a high risk that the infected fish will die from a lack of oxygen due to the massive spread in the gill tissue.
Due to its photosynthetic properties, treatment against P. pillulare in the aquarium should be carried out without lighting. Quinine hydrochloride (prescription only) or copper sulphate (be careful with lower animals and catfish) can be used as medication . In the over-the-counter trade, active ingredients with 2-amino-5-nitrothiazole are just as effective against Piscinoodinium pillulare .
swell
- Rudolf W. Hoffmann: Fish diseases. Eugen Ulmer, Stuttgart 2005, ISBN 3-8252-8241-4 .
- Dieter Untergasser: Diseases of the aquarium fish. Franckh-Kosmos, Stuttgart 2006, ISBN 3-440-10264-5 , pp. 106-107.
- Rüdiger Spangenberg: Oodinium infestation (Oodinosis). In: Claus Schaefer, Torsten Schröer (Hrsg.): The large lexicon of aquaristics. Eugen Ulmer, Stuttgart 2004, ISBN 3-8001-7497-9 , p. 720.