Ceratophyllum demersum, commonly known as Hornwort, is a popular and highly adaptable aquatic plant used in freshwater aquariums. This species is unique because it is completely rootless, absorbing all necessary nutrients directly from the water column through its dense, needle-like foliage. Hornwort is valued for its extremely fast growth rate, which allows it to efficiently consume excess nitrates and phosphates, thereby promoting better water quality and inhibiting algae growth. Its bushy structure provides excellent shelter for fish fry and small invertebrates.
Initial Preparation and Handling
Before introducing Hornwort into an established aquarium, a careful preparation process is necessary to ensure the health of your existing inhabitants. Start by thoroughly inspecting the newly acquired stems for any hitchhikers, such as pest snails or their egg clutches, which may have been inadvertently transported with the plant. A gentle, thorough rinsing under cool, dechlorinated water will help dislodge any debris and surface contaminants.
It is common for Hornwort to have some brown or damaged portions, especially near the cut ends where the plant was harvested. Use a sharp pair of aquascaping scissors to trim away any discolored or decaying segments. This material will decompose quickly in the tank and contribute to excess organic waste. Trimming helps the plant acclimate more smoothly and reduces the likelihood of an initial “melt” or excessive needle shedding once it is submerged.
Methods for Installing Hornwort in an Aquarium
Due to its rootless nature, the method for placing Hornwort in the aquarium differs significantly from traditional rooted stem plants. The simplest approach is to allow the stems to float freely at the water’s surface, which is how the plant naturally grows in the wild. Floating Hornwort creates a dense, green canopy that provides natural shading and maximizes the plant’s access to light and atmospheric carbon dioxide, often resulting in the fastest growth. Simply release the prepared bundles onto the water, allowing the stems to spread out and form a floating mat.
Alternatively, many aquarists choose to anchor Hornwort to the substrate for a more structured, background appearance. Since the plant cannot form true roots, the stems should never be buried deep into the gravel or sand, as the lack of oxygen will cause the buried portion to decay and rot. Instead, the cut end of the stem can be lightly wedged into the substrate just enough to hold it upright, or secured using a specialized plant weight made of ceramic or lead-free metal.
Securing the stems to hardscape elements like driftwood or rock is a reliable method for submerging the plant. Stems can be loosely tied in small bunches using cotton thread or fishing line, which holds the plant in place until it becomes naturally entangled with the hardscape. When anchoring, ensure the thread or weight does not tightly constrict the stem, as this can damage the vascular tissue and impede nutrient flow. This allows the Hornwort to function as a dense, submerged bush, ideal for creating visual depth in the background.
Ensuring Long-Term Health and Growth
Once Hornwort is situated in the aquarium, its continued success relies on maintaining favorable environmental conditions, which are notably flexible for this hardy species. The plant is highly tolerant of a wide range of temperatures, thriving in conditions from approximately 59°F to 86°F, making it suitable for both coldwater and tropical setups. It also adapts well to various water chemistries, tolerating a pH range between 6.0 and 8.0, and both soft and moderately hard water.
Hornwort absorbs the majority of its nutrition directly from the water column, primarily consuming nitrogenous compounds like nitrates and ammonia. Because of this aggressive nutrient uptake, the plant benefits greatly from regular doses of liquid fertilizer containing micronutrients like iron and potassium, especially if the tank is heavily planted. While the plant can grow effectively under low light conditions, providing moderate light for about 10 hours a day encourages denser, more vibrant growth.
Routine trimming is required to manage Hornwort’s rapid growth, as it can quickly shade out other plants or crowd the surface. Trimming involves simply snipping the stems to the desired length, and all cuttings can be floated or re-anchored to propagate new plants. Hornwort commonly sheds its small, needle-like leaves when first introduced or after a sudden shift in water parameters. This initial shedding is typically a temporary adjustment phase, but the fallen needles should be removed during water changes to prevent decomposition and fouling the water.