Eurasian water milfoil; Myriophyllum spicatum
Specifically refers to the aquatic plant Myriophyllum spicatum. Colloquial term used in aquarium and pond contexts.
See also: ホザキノフサモ
aquarium plant; hornwort; waterweed
Broadly used for various aquatic plants kept in goldfish tanks, including hornwort and similar species. Not a strict botanical term.
I bought some aquarium plants at the pet shop.
Eurasian water milfoil is often placed in goldfish tanks.
Compound of 金魚 (goldfish) and 藻 (algae/waterweed). The term likely originated from the common use of these plants in goldfish aquariums.