An anemone killing mixture comprises effective amounts of calcium hydroxide and non-iodized salt dissolved into and mixed in boiling purified water. A method of killing Aiptasia and Majana anemones in aquariums comprises filling a dispenser with an anemone killing mixture, comprising water and effective amounts of calcium hydroxide, placing a tip of the filled dispenser near a mouth of an anemone and dispensing a small amount of the mixture such that it is consumed by the anemone.