Riccia fluitans - Tissue Culture

Riccia fluitans: The Floating Crystalwort

Riccia fluitans, commonly known as Floating Crystalwort or simply Crystalwort, is a unique tissue culture that gained immense popularity in the aquascaping hobby after being pioneered by the late master aquascaper, Takashi Amano. Naturally a free-floating plant, it is now famous for its ability to be grown submerged, attached to hardscape to create a brilliant, dense, moss-like carpet or bush of bright green growth.

As a floating plant, Riccia fluitans is quite undemanding, requiring only moderate light. However, when this tissue culture is grown submerged as a foreground accent, its care requirements escalate. Under high light and with the addition of CO₂, it develops tiny, vibrant green tips that actively release oxygen bubbles (a phenomenon known as "pearling"), creating a spectacular visual effect. Because it is highly buoyant, securing it to a surface (usually a flat rock or mesh) is mandatory for any submerged application.

Care & Aquascaping Tips:

• Floating Use: When allowed to float, it forms thick, tangled mats just beneath the surface, providing excellent shelter and shade for fish fry, shrimp, and small, shy fish. In this form, high light and CO₂ are not essential.
• Carpeting Use (Foreground/Epiphyte): For the iconic, dense submerged carpet, you must tie or net it down to rocks, driftwood, or a stainless steel mesh to prevent it from floating. It does not have roots to anchor itself into the substrate.
• Lighting: Requires Bright/High light to maintain its compact, low-growing carpet form and to achieve that desirable "pearling" effect. In low light, it will become stringy, thin, and quickly detach to float.
• CO₂ Injection: Highly Recommended for submerged growth. While not strictly necessary, CO₂ significantly promotes dense, healthy, and compact growth, which is critical for maintaining the carpet.
• Trimming: This plant is a fast grower and is high-maintenance when used as a carpet. It requires frequent, regular trimming to encourage lateral growth and prevent the lower layers from suffocating, turning brown, and causing the entire mat to detach and float to the surface.
• Compatibility: Due to its delicate structure, avoid housing it with large, aggressive, or herbivorous fish that may graze on or disturb the fine thalli. It is perfect for shrimp tanks and nature aquariums.

Quick Facts

• Scientific Name: Riccia fluitans
• Primary Common Name: Riccia fluitans
• Other Common Names: Floating Crystalwort, Crystalwort, Slender Riccia, Floating Liverwort
• Origin: Cosmopolitan (Found worldwide)
• Max Size: Forms mats up to 2 cm (0.8 inches) thick
• Temperament: Peaceful (Plant)
• Care Level: Easy (Floating) / Moderate to Difficult (Carpeting)
• Lighting: Low/Moderate (Floating) / High (Carpeting)
• CO₂ Requirement: Not necessary (Floating) / Highly Recommended (Carpeting)
• Placement: Floating / Foreground Carpet / Epiphyte