Anubias is a genus of hardy aquatic plants known for their slow growth and tolerance to a wide range of water conditions, making them highly popular among beginning and low-tech aquarium keepers. These plants are native to the dense, shaded rainforests of West Africa, where they naturally grow along riverbanks under a thick tree canopy. Understanding this origin is paramount, as it explains why Anubias is a low-light demanding plant. Proper light management is the primary factor that prevents the most common problem hobbyists face: persistent algae growth on their broad, slow-growing leaves.
Defining Anubias Light Needs
The concept of “low light” for Anubias translates into specific, measurable parameters that relate to both light intensity and duration. For the technical hobbyist, the appropriate light intensity is measured using Photosynthetically Active Radiation (PAR), which quantifies the light available for photosynthesis. Anubias thrives in a PAR range generally between 15 and 30 micromoles per square meter per second at the leaf level. Exceeding this range does not significantly speed up the plant’s genetically limited growth rate, but it supplies surplus energy that opportunistic algae species can readily use.
The duration of light, or photoperiod, must also be carefully controlled to prevent stress and algae proliferation. A consistent photoperiod of six to eight hours per day is entirely sufficient for Anubias to conduct necessary photosynthesis and remain healthy. Running the lights for longer periods, such as ten to twelve hours, increases the risk of algae without providing any measurable benefit to the plant.
Practical Lighting Solutions
Achieving the correct low-light conditions often starts with selecting appropriate lighting fixtures for the aquarium setup. Modern LED lighting systems are the standard, offering high energy efficiency and adjustable features that make them ideal for managing Anubias requirements. When choosing an LED fixture, look for models that include dimmability or multiple intensity settings, which provide the ability to fine-tune the light output.
Using a lower-wattage fixture is often the simplest and most effective way to ensure the plant is not overwhelmed with light intensity. A light designed for smaller or shallower tanks can provide the perfect 15-30 PAR range, avoiding the need for extreme fixture height adjustments. The color spectrum is less critical for Anubias, but full-spectrum white light is preferred for both plant health and aesthetic viewing.
Strategic Placement and Attachment
Anubias species are characterized as epiphytes, meaning they naturally grow attached to surfaces like rocks and driftwood rather than rooted in the substrate. The plant’s thick, horizontal stem, known as the rhizome, must remain exposed to the water column and should never be buried in the gravel or sand, as this will cause it to rot.
Attachment to hardscape, using aquarium-safe super glue or cotton thread, allows the plant to be strategically positioned to manage light exposure. Even in tanks running high-intensity lighting for demanding plants, Anubias can thrive by utilizing existing shading. Placing the attached plant underneath the overhang of a large piece of driftwood or tucked beneath a broad-leafed sword plant effectively reduces the PAR reaching the leaves. These shaded zones recreate the dappled, low-light environment of its West African origins.
Recognizing Signs of Light Imbalance
Diagnosing issues with Anubias often involves observing the leaves for visual cues that indicate an imbalance in light exposure. The most common problem is too much light, which typically manifests as the rapid colonization of Green Spot Algae (GSA) directly on the surface of the leaves. Because Anubias leaves grow slowly and last for a long time, they provide a stable, undisturbed surface for algae to attach.
Another symptom of excessive light is a bleached or pale yellow appearance on the leaves. This signals that the plant is stressed and receiving more light energy than its cells can safely process.
Conversely, insufficient light is a less frequent issue but can be identified by extremely slow growth or leaves that appear abnormally dark green. This indicates the plant is maximizing its chlorophyll production to capture minimal light. Corrective action for too much light involves moving the plant to a shadier location or reducing the photoperiod. Insufficient light requires gradually moving the plant closer to the light source or increasing the duration by one or two hours.