Ceratopteris cornuta

Geographical Origin and Habitat: Ceratopteris cornuta is native to tropical Africa, Madagascar, and parts of Asia, where it inhabits stagnant ponds, warm swamps, and calm riverbanks. It grows in both submersed and floating forms in nutrient-rich, sunlit waters, adapting well to seasonal fluctuations.

Taxonomy & Genetics: Belonging to the Pteridaceae family, it is often confused with *Ceratopteris thalictroides*, but Ceratopteris cornuta features submersed leaves with wider, less finely divided lobes. Genetically, it is a polyploid fern with an extraordinary capacity for vegetative reproduction via adventitious buds.

Physical Structure: It forms a dense, robust rosette. Submersed leaves are broad, lobed, and fleshy, while the floating leaves are simpler and more expanded. The root system of the floating form is extremely dense, dark, and highly branched, hanging down several centimeters into the water column.

Color & Texture: The leaves exhibit a bright, fresh light green. The texture is soft, fleshy, and herbaceous, with internal air pockets that facilitate floating. The lobed yet broad shape of the leaves provides an excellent visual contrast and a lush, natural feel.

Lighting & CO2: It requires medium to high light levels to support its very fast metabolism. Floating specimens benefit from direct overhead light; submersed plants need strong light to prevent the rosette from thinning out. CO2 injection is not required but stimulates even faster growth.

Nutrition & Substrate: It is a heavy nutrient feeder, consuming large quantities of nitrates, phosphates, and potassium, making it useful for controlling algae. If rooted, it prefers a soft, fertile substrate, though nutrient absorption is primarily through the

Water Chemistry: It is exceptionally tolerant of a wide range of water parameters, adapting to pH 5.0 to 8.0 and KH 0 to 21. The optimal temperature is between 18°C and 30°C. Regular water changes are recommended to replenish nutrients consumed by its rapid growth.

Space Management & Placement: Due to its fast growth and large potential size, it is best placed in the background or midground of spacious tanks. As a floating plant, it must be thinned regularly to prevent it from covering the entire surface and shading out plants below.

Pruning: Prune by removing older, larger, or damaged fronds at the base of the rosette. When kept floating, simply remove excess daughter plants. The plant propagates itself easily by producing small adventitious plantlets along the margins of mature leaves.

Risks & Diseases: The fronds are soft and fragile, making them susceptible to physical damage from strong currents or large herbivorous fish. Nutrient deficiencies (especially iron and nitrogen) cause the leaves to turn yellow, translucent, and rot.