Ichthyophthiriosis - cause of significant losses of carp fingerlings

Ichthyophthiriosis is widespread parasitic disease of fi shes caused by a ciliated protozoan, Ichthyophthirius multifi lis. Th is parasite is capable of aff ecting most of species of freshwater fi shes, including all cyprinids. Th e parasites usually can be found on skin and gill in the form of white pro- minent spots 0.1-1 mm in diameter, which looks as if the fi sh was sprin- kled with grits. Within these tissues, infections cause localized lymphocyte infi ltration, focal necrosis and varying degrees of epithelial proliferation. Investigations were carrieed out during a last 10 years, while monitoring the health condition of carp fi sh. Diagnosis of ichthyophthiriosis was perfor- med by clinical and microscopic examination. Disease was present in carps throughout their life, but the most susceptible were young categories. Th e parasites were present on the skin and gills earlier in 10-day-old fi ngerlings. Th e outbreaks are most common in spring, aſt er overwintering when wa- ter temperatures increase and also does the parasite replication rate. High stock density, water quality and poor condition contribute to illness. Since the disease causes signifi cant losses of carp fi ngerlings it is necessary to per- form its adequate controls and therapy. In order to prevent the disease it is need to to rear young fi sh separately from other fi sh categories, prevent weed fi shes from entering the ponds and employ hygienic and prophylac- tic measures. All technological measures which can improve the condition of fi sh are most eff ective against ichthyophthiriosis. It is important to add lime into the pond from time to time. Eff ective chemical treatments for I. multifiliis include copper sulfate, potassium permanganate, malachite gre- en, salt and formalin. Malachite green is a teratogen, and prohibited for use, while copper sulfate, potassium permanganate and formalin are also under currently reviewing for the use as parasiticides in food fi sh. So that, non-iodized salt is the only permitted and safe therapeutic for the moment.