Species description

Care, breeding and tankmates

Plant profile

Placement

Floating

It is a surface-dwelling floating plant that provides an excellent canopy for the aquarium. It should be allowed to drift freely or contained within a floating ring to prevent it from covering the entire surface. It is particularly useful for shading Anubias or Cryptocoryne species that prefer lower light environments.

Botanical form

Floating, Fern

This floating fern is characterized by its triangular or feathery frond shape, giving it a somewhat more structured look than other Azolla species. The small, overlapping leaves are water-repellent, ensuring the plant stays afloat. It develops short, feathery roots that extend down into the water column.

Growth

Fast

In an aquarium with good lighting and nutrient availability, Azolla pinnata grows extremely fast. It can double its mass in mere days, actively stripping excess nutrients from the water and suppressing algae growth. Frequent culling is necessary to keep it from completely blocking out light to the lower sections of the tank.

Substrate

None

Like other members of its genus, this fern floats freely and requires zero substrate for survival or structural anchoring. Its fine, feathery roots hang vertically into the water column to efficiently absorb dissolved liquid fertilizers. The lack of substrate dependency makes it an excellent choice for bare-bottom tanks or heavily stocked setups prioritizing water column nutrient management.

Column fertilization

Recommended

Because it lacks a connection to the soil, it is entirely dependent on water column fertilization. Dosing a high-quality liquid fertilizer will ensure it receives the necessary micronutrients for healthy growth and coloration. Care should be taken to ensure it does not outcompete submerged plants for nutrients.

Root fertilization

None

Root fertilization is fundamentally inapplicable to Azolla pinnata. Substrate nutrients are entirely out of reach for this floating fern, meaning all its nutritional needs must be met via the water.

Trimming

Occasional

Trimming is not a practice used with this plant. Instead, aquarists must physically remove portions of the floating mat using a net or hands. Regular removal is essential to maintain a healthy balance of light and gas exchange in the aquarium. Never dispose of this plant in natural waterways.

Propagation

Division, Fragmentation

Propagation is simple and automatic, occurring through vegetative fragmentation. As the fronds grow and branch out, pieces naturally detach to form new, independent plants. This rapid, passive propagation means it can quickly repopulate the surface after a heavy trimming.

Sensitivity

Moderate

Azolla pinnata prefers still to gently moving water, as strong surface currents or splashing from filter returns can damage its fronds and cause them to rot. It is also susceptible to decay if the tops of its leaves are constantly wet from condensation. It handles a broad range of temperatures but grows best in warmer conditions.

Layout role

Floating

It acts as a natural shade cloth, dimming the light for the aquascape below while providing a beautiful, textured surface cover. The small, trailing roots offer an excellent grazing and hiding spot for shrimp and fry. The reddish tint it can achieve provides a unique pop of color at the very top of the tank.