Ichthyophthiriasis, commonly known as white spot disease, occurs in both wild and cultured fish and is responsible for heavy economic losses to the aquaculture industry. In past decade, several chemical therapeutants were used to treat ichthyophthiriasis, but the effective drugs, such as malachite green, have been banned for use in food fish due to its genotoxic and carcinogenic properties. To find efficacious drugs to control Ichthyophthirius multifiliis (Ich), whole Eclipta alba plants and dried root of Arctium lappa were evaluated for their antiprotozoal activity. E. alba and A. lappa extracts significantly reduced the survival of Ich trophonts and theronts. In vitro, the E. alba and A. lappa methanol extracts killed all trophonts at 3200 mg l-1. All trophonts were killed after exposure to E. alba aqueous extract at 3200 mg l-1. The methanol extracts of E. alba and A. lappa killed 100% of I. multifiliis theronts at 400 mg l-1 and 800 mg l-1, respectively. The aqueous extract of E. alba and A. lappa killed 100% of I. mulitifiliis theronts at 1600 mg l-1 and 3200 mg l-1, respectively. E. alba and A. lappa extracts may be new and efficacious drugs for the control of ichthyophthiriasis.
Keywords: Arctium lappa; Eclipta alba; Ichthyophthirius multifiliis; fish; parasite.
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