The Anubias genus of aquatic plants originates in the shaded, slow-moving rivers of West and Central Africa. These plants are known for their impressive hardiness, thick, dark green leaves, and minimal maintenance requirements. The defining trait of this genus, however, is its extremely slow growth speed, which sets it apart from nearly all other common aquarium flora.
Defining the Growth Rate
Anubias is consistently ranked among the slowest-growing aquatic plants available today. This slow pace results from the plant’s evolution in low-light, low-nutrient environments, prioritizing survival over rapid expansion. Its slow metabolism allows it to thrive on limited resources where faster-growing species would quickly starve.
Quantifying this growth speed shows how slowly Anubias spreads. In a healthy, low-technology aquarium, the typical growth rate is the production of approximately one new leaf every three to six weeks. New plants may show no visible change for a couple of months while acclimating. This is in stark contrast to fast-growing stem plants, such as Ludwigia or Rotala, which can grow several inches weekly and require frequent trimming.
Environmental Conditions That Impact Speed
While Anubias will never be a fast-growing plant, optimizing its environment can accelerate its growth from “very slow” to “steady and noticeable.” Light intensity is one factor that can be manipulated, though Anubias is naturally a low-light plant. Increasing the light to a medium-intensity range can gently push growth without causing stress. Too much direct, high-intensity light leads to rampant algae growth on the tough, long-lived leaves, which ultimately hinders the plant’s health.
Nutrient availability in the water column also plays a significant role. Anubias is a water column feeder, absorbing nutrients primarily through its leaves and roots. Although its nutrient requirements are low due to its slow metabolism, the plant benefits greatly from liquid fertilization, especially with micronutrients like iron. If new leaves appear pale or yellow, it often indicates a deficiency in these essential trace elements.
The most significant accelerator for Anubias growth is the injection of carbon dioxide (CO2) into the water. While not strictly necessary for the plant’s survival, pressurized CO2 injection can robustly increase the growth rate and result in healthier, more algae-resistant foliage. In a highly optimized setup, the plant may produce a new leaf every two to three weeks, significantly faster than in a basic environment. However, even under these ideal conditions, the growth remains slow compared to most other aquarium plants.
The Central Role of the Rhizome in Growth
The unique anatomy of Anubias dictates its slow, horizontal growth pattern, which is centered entirely on a structure called the rhizome. The rhizome is a thick, fleshy, horizontal stem from which all new leaves and roots emerge. This structure houses the plant’s growth points and is responsible for its entire vegetative spread.
A proper understanding of the rhizome is paramount for successful cultivation, as it explains the correct planting technique. The rhizome must never be buried in the substrate, whether gravel or soil. Burying this horizontal stem prevents oxygen from reaching the tissue, which will cause the plant to rot and eventually die. Instead, Anubias must be attached to driftwood or rock using thread or superglue, allowing the roots to anchor themselves while the rhizome remains exposed to the water column.
Propagation of the plant is also performed by directly manipulating the rhizome. Once the stem has grown sufficiently long, a sharp, clean cut can divide it into smaller segments. Each new segment, provided it has a few leaves attached, will then develop into a separate, independent plant. This method allows the aquarist to multiply their Anubias stock while maintaining the integrity of the mother plant.