Fairy Moss on the Surface:

Fairy Moss (Azolla caroliniana) is a free-floating aquatic fern native to eastern North America and to Central and South America, where it forms surface mats across near-stagnant ponds, wetlands, and ditches. Each leaf hosts a nitrogen-fixing cyanobacterium, and the plant takes up phosphorus and other nutrients from the water. In the Botanical Method Aquarium, blackwater aquariums, and biotope aquariums, Azolla provides refuge at the surface for aquarium inhabitants and a large surface area for biofilm colonization.

Essential Details

• Care Level: Easy
• Growth Habit: Continuous, forms a surface mat
• Light: Medium
• CO2: Not Necessary
• Propagation: Division
• Tint Tolerance: Low to High
• Habitat Location: Eastern North America through Central and South America
• Optimal For: Betta fish, shrimp, fry, and other small species suited to surface cover and biofilm grazing in blackwater and biotope aquariums
• Use with Caution: Rinse before introducing; may carry beneficial hitchhiking snails, snail eggs, or duckweed from the grow-out ponds
• Size Range: Individual strings of leaves form bunches up to 3 inches long that break apart easily
• Quantities: One 4 oz cup portion, about a golfball size amount

Fairy Moss for Planted Aquariums & Blackwater Biotopes

Fairy Moss forms a floating mat that provides shade to the water below and limits the light available to nuisance algae. Biofilm readily forms on the roots hanging beneath, providing supplemental nutrition to shrimp, fry, and microfauna such as copepods and ostracods, and giving them a grazing surface at the top of the aquarium. Azolla also absorbs phosphorus and other nutrients from the water column, and when we thin the mat, those nutrients leave the aquarium, similar to the export of nutrients during a water exchange.

Each Fairy Moss leaf has a small cavity that hosts a nitrogen-fixing cyanobacterium, which supplies the plant with nitrogen from the atmosphere. Tint reduces the light that reaches the water column, and light drives plant growth. A floating plant sits above most of that tint, so Azolla receives the full output of the aquarium light in dark and clear water alike. Light intensity heavily influences its color. The fronds stay green under gentler light and shift through rust orange to pink and red under the strongest light.

Fairy Moss propagates by division, and each portion will keep growing wherever it is propagated. Azolla grows in near-stagnant water, so we position filter returns and bubbles to keep the surface as still as possible. As the mat of Azolla fills in, we thin it by hand, ensuring part of the water surface remains open so light and gas exchange reach the plants and fishes below. We compost excess Fairy Moss and never release aquarium plants into local ponds, ditches, or waterways.

Beneath the Leaves: Azolla caroliniana in the Wild

Azolla caroliniana is native to eastern North America, from Ontario southward through the eastern United States, and to the Caribbean and Central and South America. It floats on slow-moving or stagnant water in ponds, lakes, marshes, swamps, streams, and ditches, and it is most often reported from reed swamps. In temperate populations, the mat turns from green to rusty red as autumn arrives.

Where a botanical contributes as it breaks down, an aquatic plant is living and contributes as it grows. So let them grow. Mother Nature leads the way.

Sustainability Note:

Please select a heat/cold pack if necessary. Check your local weather before ordering to avoid any shipment holds or cancellations. All Plants may contain snails or snail eggs. We keep them in all of our aquariums for the benefits they provide. Our blackwater aquarium plants are provided in cooperation with PNW Bettas in adherence to their Shipping and DOA Policies. Your curated selection will arrive in their packaging, separate from your botanical, wood & merch orders.