Giant Duckweed (Spirodela polyrhiza)

Spirodela polyrhiza, the Giant Duckweed or Greater Duckweed, is the largest member of the duckweed family, producing rounded, flat fronds noticeably larger than the familiar Lemna minor. Each frond carries a cluster of multiple roots dangling below the surface — a distinguishing characteristic that is also highly attractive to fish fry and small invertebrates seeking shelter beneath the surface. Being larger than common duckweed, it is significantly easier to net and remove when thinning is required, making it a more manageable surface plant for aquarists who appreciate the benefits of floating coverage without the frustration of near-microscopic common duckweed escaping net holes. Excellent for nutrient export, surface shading, and providing refuge for surface-dwelling species.

Float freely on the water surface under low to medium light. Grows rapidly — thin regularly to prevent complete surface coverage. Easy to remove with a fine net or by hand. No fertilization required — absorbs nutrients directly from the water column. Ideal for breeding tanks and fry tanks where surface plant cover is desired. Avoid strong surface agitation which can cause fronds to sink.