Concentrated treating compound to clear parasitic infections of fish living in aquaria or ponds. Produced by Alpha-Biocare GmbH (Düsseldorf, Germany, www.alphabiocare.de) and sold by Fa. Sera, Heinsberg, Germany (www.sera.de). The product includes 10 mg emamectin benzoate per ml, macrogol 300 propylene carbonate, and denatonium benzoate. The following ectoparasites are killed: carp lice (e.g., Argulus species), gill crustaceans (e.g., Ergasilus species and isopods), and anchor worms (e.g., Lernaea species). The product is diluted in the water of aquaria and/or ponds. Doses: 2 ml Argulol® per 100 l water for 3 h in aquaria or 5 ml Argulol® per 1,000 l water in ponds (see declaration sheet).