Ceratophyllum demersum

Scientific name: Ceratophyllum demersum

Family: Ceratophyllaceae

Maximum size reached under cultivation: 10 - 80 cm (3.94 - 31.5 inch)

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Recommended pH range: 6.2 - 7.5

Recommended water hardness: 4 - 18°dGH (71.43 - 321.43ppm)

0°C 32°F30°C 86°F

Recommended temperature range: 21 - 28 °C (69.8 - 82.4°F)

Preferred propagation method: Cuttings

Native to: Cosmopolitan

Growth rate: Fast

Recommended substrate: Sand

Lighting requirements: Bright

Ideal placement in tank: Background

Common Name

Rigid Hornwort

Origin

Ceratophyllum demersum, commonly known as Rigid Hornwort, is a highly adaptable aquatic plant found across the globe in a variety of freshwater habitats. It thrives in temperate and tropical regions, and its widespread distribution includes North America, Europe, Asia, Africa, and parts of Australia. Because of its resilience, this plant can flourish in lakes, rivers, ponds, and slow-moving streams, making it one of the most versatile plants for aquarium use.

Planting Area

Floating or background placement when loosely anchored. Ceratophyllum demersum is most often used as a floating plant due to its lack of true roots. It can also be gently weighed down or secured between decorations if background placement is desired. Avoid burying it in the substrate, as this may lead to decay.

Propagation

Rigid Hornwort is extremely easy to propagate, making it an excellent choice for both beginner and experienced aquarists. Propagation is achieved through cuttings taken from anywhere along the plant’s stem. These cuttings do not require any special care, as they will naturally develop a rudimentary root structure when placed in the water. The plant can be used as a floating species or anchored in the substrate. To anchor it, remove a few lower leaves from the stem to expose a bare section, and gently place this into the substrate without damaging the stem. Even without traditional roots, the plant will anchor itself over time.

Difficulty

Easy

Short Description

Rigid Hornwort is a fast-growing, undemanding plant that can thrive in a variety of water conditions, making it a popular choice for many aquariums. It lacks a true root system but compensates by absorbing nutrients directly from the water column, which allows it to grow effectively as a floating plant. When used as a floating species, Hornwort helps improve water quality by soaking up excess nitrates, and it also releases allelopathic substances that can inhibit algae growth, making it a natural solution for algae control in planted tanks.

This plant is also valued for its ability to provide excellent cover for fish fry and shrimp, creating a safe space for small, vulnerable species to hide. In addition, its fast growth can help create a dense, forest-like appearance in the background of the aquarium, or it can simply float freely at the water’s surface to diffuse light and create a more natural, shaded environment.

Hornwort is highly adaptable and can tolerate a wide range of water parameters, from soft to hard water and temperatures between 15-30°C (59-86°F). Its ease of care and beneficial properties make it an excellent addition to both low-maintenance community tanks and more advanced planted setups.

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