Translation guide
Blue-green algae refers to a group of photosynthetic bacteria, often called cyanobacteria. In Japanese, the most common term is 藍藻 (らんそう), but in everyday contexts, especially regarding blooms in water, アオコ is widely used. Scientific and technical contexts may use シアノバクテリア.
Referring to the organism in biological or general contexts.
The standard Japanese term for blue-green algae (cyanobacteria). Used in biology and general descriptions.
Blue-green algae are bacteria that perform photosynthesis.
Loanword from English 'cyanobacteria'. Common in scientific and technical writing.
Some cyanobacteria have nitrogen-fixing ability.
Referring to the visible greenish scum or bloom on ponds, lakes, or aquariums.
The most common everyday word for blue-green algae blooms. Often seen in news about water quality.
Blue-green algae appeared in the pond.
Literally 'water flower', a poetic term for algal blooms, including blue-green algae. Used in literary or descriptive contexts.
Referring to the slimy blue-green coating that grows in fish tanks.
In aquarium hobby contexts, 藍藻 (らんそう) is the standard term, though sometimes also called シアノバクテリア.
I'm having trouble with blue-green algae growing in my aquarium.
Use アオコ for visible blooms in natural water bodies. Use 藍藻 or シアノバクテリア for scientific or biological discussions. In aquarium contexts, 藍藻 is most common.
In summer, water blooms can be seen on the lake.