DAO 64:69-76 (2005)  -  doi:10.3354/dao064069

Treatment of ichthyophthiriasis after malachite green. I. Concrete tanks at salmonid farms

Päivi Rintamäki-Kinnunen1,*, Mika Rahkonen2, Anna-Liisa Mannermaa-Keränen3, Lotta-Riina Suomalainen2, Heikki Mykrä2, E. Tellervo Valtonen2

1Department of Biology, University of Oulu, PO Box 3000, 90014 Oulu, Finland
2Department of Biological and Environmental Science, University of Jyväskylä, PO Box 35, 40014 Jyväskylä, Finland
3Finnish Game and Fisheries Research Institute, Manamansalontie 90, 88300 Paltamo, Finland

ABSTRACT: Since the use of malachite green was banned in many European countries, new alternative treatments have been tested to prevent white spot disease caused by Ichthyophthirius multifiliis. We tested formalin, potassium permanganate (KMnO4), chloramine-T, hydrogen peroxide (H2O2) and Per Aqua or Desirox alone or in combinations of 2 chemicals, one of which was always formalin, in 50 m2 concrete tanks at 2 farms producing salmon Salmo salar smolt in 2001 and 2002. Both Per Aqua and Desirox are combinations of peracetic acid, acetic acid and hydrogen peroxide. The alternative chemicals or their combinations can be used successfully to lower the parasite burden to such a level that no high mortality occurs during the first 4 wk after the start of an infection. This period of time allows the fish to develop immunity against these ciliates, and treatments can be reduced and stopped in due course. I. multifiliis decreased in number 3 to 4 wk after the beginning of the infection in all the treatments. Large differences in parasite burden and mortality occurred among the replicates in all except the Desirox-formalin tanks, which means that they are not as reliable as the malachite green-formalin used previously. It was also evident that the chemicals and their concentrations must be planned carefully to suit the conditions on each farm.


KEY WORDS: Ichthyophthirius multifiliis · Salmo salar · Fish farming · Immunity · Alternative chemicals


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