Hornwort Aquarium Plant/Ceratophyllum It can adapt to almost any water type, and can tolerate a wide extreme of temperatures. The allelopathic abilities of Hornwort, can inhibit the growth of blue-green algae (cyanobacteria). This is an alga that can quickly get out of control in conditions with too much light or lots of organic waste. It it also often used in newly established fish tanks, or fish tanks with water quality problems. The fast growing plant will help balance out the water quality, and numerous fish tank crashes have been avoided by adding a large bunch of hornwort when there is an ammonia spike in an aquarium. $5.00 large bunch. Email or text only please. Can deliver or arrange pickup in Victoria.