American eelgrass

The plant sold as giant Vallisneria or American eelgrass in the aquarium trade rarely matches its scientific label. Flowgrow notes that the name Vallisneria americana is consistently misapplied to other species — most often Vallisneria australis or Vallisneria neotropicalis — and that the true V. americana is probably not cultivated in aquariums. What reaches the trade is a tall, fast-growing rosette plant capable of sending leaves past 60 cm under good light, making it a staple for the background of large tanks. It spreads through runners and fills in gaps without much intervention. Lighting can be moderate to high; CO2 supplementation is not required but speeds up growth noticeably. Temperature tolerance is broad, from around 18 to 30 °C, and pH can range from 6.5 to 8.5 in practice. Liquid fertiliser — particularly iron and potassium — helps older leaves stay green rather than yellowing off. Because the true identity is uncertain, verify with the seller whether the plant stays a manageable size or pushes toward 100 cm leaves in a high-light setup.