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Ichthyophthirius , (often short Ichthyo called), also white spot disease , white point disease , white spot disease or semolina grains disease , is a common parasitic disease in freshwater fish. Ichthyophthiriosis is one of the most important diseases in freshwater aquariums and pond management .


Ichthyophthirius multifiliis

Ichthyophthiriosis is caused by the ciliate Ichthyophthirius multifiliis . This globally occurring ectoparasite reaches a size of up to 1 mm in its vegetative form. Outstanding features are a horseshoe-shaped large core and a round small core .

Life cycle of Ichthyophthirius multifiliis

The parasite lives in the epidermis or in the epithelium of the gills of its host in cavities that are closed to the outside. Once it has matured to reproductive capacity, it breaks through the skin and leaves the host, causing the host to suffer considerable skin damage. In the water, Ichthyophthirius multifiliis sinks to the bottom, settles there and begins to form cysts . In these there are repeated divisions in up to 1000 so-called swarmers (tomites) from 50 to 70 micrometers in size. The swarmers are again capable of invading fish, but have to find a host within 70 hours. The duration of the reproduction process depends on the temperature; at four degrees Celsius it takes about six days, at 25 to 28 degrees Celsius it only takes ten to twelve hours. In tropical aquariums in particular, there can therefore be an explosion-like increase with corresponding infestation rates.


Infested cichlid

Infested fish have white nodules the size of a pinhead all over their bodies, including their fins and gills. In severe cases, the nodules can unite to form gray areas. The affected fish often show breathlessness, "fin clamps" and violent scrubbing movements. As a result, the fish becomes increasingly apathetic and lean.


The parasite cannot be controlled directly during its growth phase in the host's skin. The treatment is directed against the free-swimming swarmers. In aquariums, the water temperature can be increased slightly in order to shorten the protected development phase as a cyst. Malachite green is a suitable drug for ornamental fish , while farm fish can be treated with formalin and potassium permanganate . In the aquarium trade there are means for one-time treatment from different manufacturers. Fish that survive ichthyophthiriosis develop stable immunity .


Individual evidence

  1. ^ Rüdiger Riehl / Hans A. Baensch ; Aquarium atlas; Mergus Verlag; 12th edition, 2000; P. 913; ISBN 3882442271
  2. faunamor against Ichthyophthirius ("white spot disease") ( Memento of the original from March 16, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. at aquarium-munster.com, accessed December 26, 2014 @1@ 2Template: Webachiv / IABot / www.aquarium-munster.com
  3. Tetra Medica ContraIck at tetra.de, accessed on December 26, 2014
  4. Instructions for use at jbl.de, accessed on December 26, 2014

Web links

Commons : Ichthyophthirius multifiliis  - collection of images, videos and audio files