Vesicularia montagnei is a species of aquatic moss in the family Hypnaceae, most commonly known in the aquarium trade as Christmas moss. It is native to Southeast Asia, where it typically grows along moist riverbanks, rocks, and tree trunks in shaded, humid environments.

In aquariums, it is highly prized as a decorative and functional plant. Its fronds grow in overlapping, triangular, “Christmas tree–like” patterns, giving it a distinctive, dense, and bushy appearance. The moss attaches itself to hard surfaces such as driftwood, stones, and substrate, spreading over time to form lush green mats or cascading curtains.

Key characteristics:

• Growth form: Creeping and attaching, with horizontal branching that resembles fir tree branches.

• Size: Generally grows up to 3–5 cm tall in aquariums but spreads broadly over surfaces.

• Light requirements: Tolerates low to medium light, but displays more compact, bright green growth in moderate lighting.

• CO₂/fertilizer: Does not require CO₂ injection but benefits from it, along with nutrient supplementation.

• Water parameters: Adaptable; thrives in a wide temperature range (20–28 °C / 68–82 °F).

Uses in aquascaping:

• Provides cover and grazing surfaces for shrimp and small fish.

• Creates a natural, forest-like aesthetic when attached to driftwood or rocks.

• Serves as a spawning site for some fish due to its fine branching structure.