Bolbitis heudelotii

The African Water Fern, also known as the Congo Fern, is a highly prized aquatic plant originating from the fast-flowing rivers of Africa. Its distinct appearance, characterized by deep green, finely textured, and somewhat transparent leaves (fronds), makes it a stunning centerpiece or accent in a planted aquarium. This species is best suited for the middle ground of the tank, where its slow, steady growth will eventually form a dense, bushy clump.

As an epiphytic plant, its success in an aquarium hinges on proper placement. The thick, creeping rhizome must never be buried under the substrate, as this will lead to rot and the plant's eventual death. Instead, it should be attached to hardscape elements like driftwood or porous rock using fishing line, cotton thread, or aquarium-safe cyanoacrylate glue. Over time, its dark, wiry roots will firmly anchor the plant to the surface. It thrives in established aquariums with stable water parameters, showing a preference for slightly acidic to neutral water, though it is adaptable to a reasonably broad range of hardness levels. It is a strictly freshwater species that will not tolerate elevated salinity.

Optimal health and appearance are achieved with good water circulation, which mimics its natural riverine habitat. This flow delivers nutrients directly to the fronds and prevents detritus from settling on the rhizome, a common cause of decay. While it can survive under low illumination and without CO₂ injection, its growth is noticeably more robust and compact under moderate lighting and with carbon dioxide supplementation. In lower light conditions, growth can become exceptionally slow, and the plant may struggle. Nutrient absorption is primarily from the water column, so while it is not a demanding feeder, it benefits from a comprehensive liquid fertilizer to support its deliberate growth.

Bolbitis heudelotii is a validated species within the family Dryopteridaceae, a group commonly known as the wood ferns. As a member of the Tracheophytes phylum, it is a vascular plant possessing specialized tissues for conducting water and nutrients. Its morphology is distinctly adapted to a rheophytic lifestyle, growing attached to surfaces in moving water. The primary structure is a dark, creeping rhizome that anchors the plant to hardscape using tough, wiry roots, which are primarily for attachment rather than nutrient absorption. From this rhizome emerge the fronds, which are the plant's leaves. Submersed fronds are pinnate, with an elegant, textured appearance, and are typically a dark, rich green. A notable characteristic is their translucence, which distinguishes them from many other aquatic plants. The plant exhibits a slow metabolism, reflected in its very slow growth rate, low oxygen production, and minimal CO₂ and nutrient demands. This physiology makes it well-suited to stable, mature aquatic ecosystems.

In its native African habitat, B. heudelotii colonizes rocks and submerged wood in shaded areas of streams and rivers with moderate to strong currents. This ecological niche explains its preference for good water flow and its tolerance for lower light conditions in an aquarium setting. The flow is critical for preventing sediment accumulation and delivering dissolved gases and nutrients to the leaf surfaces. While it can grow emersed, its submersed form is most popular in the aquarium trade. According to its IUCN Red List status, the species is classified as Least Concern, indicating it is currently widespread and not at immediate risk of extinction in its natural environment.

Propagating the African Water Fern is a straightforward process, though its very slow growth rate demands patience from the aquarist. The species reproduces asexually within the aquarium through rhizome division; sexual reproduction via spores is its natural method but is not a practical approach for hobbyists.

To propagate the plant, begin with a mature, healthy specimen that has a long, well-developed rhizome with abundant fronds and roots. Using sharp, sterilized scissors or a razor blade, carefully cut the rhizome into smaller sections. For the highest chance of success, each new cutting should have at least a few healthy leaves and a small bundle of roots attached. Cuttings that are too small or lack leaves may fail to establish.

Successful establishment is heavily influenced by environmental factors. New cuttings thrive in stable water conditions with good circulation, which helps prevent fungal or bacterial rot at the cut surfaces. While the plant is not demanding, providing moderate lighting can encourage the onset of new growth. As a water column feeder, access to a light regimen of liquid fertilizers can also support the development of new roots and fronds.

After separation, attach the new plantlets to a piece of driftwood or rock. Use cotton thread, fishing line, or a small amount of cyanoacrylate glue, being careful not to apply adhesive to any developing leaf buds. Crucially, ensure the rhizome is exposed to the water column and is never buried in the substrate. Be prepared for an initial dormant period where the cutting may show no visible growth as it acclimates. A key tip is to maintain clean water to prevent the cut ends of the rhizome from 'melting' or decaying. In some instances, tiny adventitious plantlets may form on older, deteriorating leaves; these can be carefully removed and grown out once they have their own small rhizome.