• Scientific name: Elodea densa
• Synonym: Anacharis densa; Philotria densa; Egeria densa
• Common name: Giant elodea, Pondweed
• Family: Hydrocharitaceae
• Group: Aquarium plants
• Max height: 80 cm
• Distribution: Worldwide
• Habitat: In stagnant or slow-moving, usually deeper waters.
• Substrate: Plain washed gravel
• Placement in aquarium: Background, middleground
• Planting density: 5-6 plants for 20 cm²
• Lighting needs: Moderate to bright
• Temperature: 10-22°C
• pH: 6,5-8
• Hardness: 8-20 NK°

Description: A popular and undemanding coldwater plant for many years, with only limited hardiness, Elodea densa grows free-floating or implanted, but can usually be kept at higher temperatures for only short periods. It adapts to soft, acid water rich in lime with higher pH-values. In comfortable conditions the species is a good oxygen provider because of its rapid growth.

Elodea is highly adaptable, fast growing, and one of the easiest aquatic plants to keep. Ideally, it prefers harder water, but will adapt to a wide range of water conditions and temperatures. With good lighting, elodea can be kept in aquariums with higher temperatures. Elodea is found in many temperate and subtropical regions throughout the world as an introduced, or "alien" species, meaning a species that does not originate from the area it is found in. In many places, particularly in Europe, fast-growing, adaptable plants such as elodea can spread quickly and cause major damage to native plants and wildlife. Therefore, it is vital that aquarists behave responsibly and do not allow aquarium plants to reach open waterways, rivers and lakes.