weed identification

common name
Nitella, Green Algae

Nitella is a green algae commonly found growing on the bottom of shallow freshwater ponds and slow flowing streams, and is particularly found in clean water.

how to identify
  • Main stem, translucent in appearance, with a whorl of branchlets.
  • Branchlets can appear very small.
  • Prefers warmer temperatures and more acidic water.
  • Soft/smooth to touch.
  • Nitella has no flower and growth will not exceed the water’s surface.
mistaken with
  • Milfoil (aquatic plant) and Hornwort (aquatic plant)
    • Milfoil appears more feather-like in its whorls, and will produce flowers
  • Chara (algae)
    • Grainy texture and will smell musty when crushed
Eurasian Water Milfoil (Mackenzie, 2016)
Eurasian Water Milfoil (Mackenzie, 2016)

Overall, Nitella algae are ecologically important organisms in freshwater ecosystems, playing roles in nutrient cycling, habitat structure, and providing food and shelter for various aquatic organisms.

What does Nitella look like?

Use these images below to help you decide whether you are dealing with Nitella.

Disadvantages of Nitella

Excessive growth of Nitella algae can lead to ecological imbalances and water quality issues, similar to the issues seen with excessive Chara growth. Effective management strategies, such as nutrient control and habitat restoration, may be necessary to mitigate the impacts of excessive Nitella growth and maintain healthy freshwater ecosystems.


Coptrol – Algaecide control designed to kill algal cells. Use on mild to severe algae blooms.

Aquatic Razer Rake – DIY Physical Removal. Ideal for mild infestations, sensitive water bodies and sensitive fish species.

prevention options

Aquatic Blue Dye – Blue dye that may reduce temperature of the water body by reducing UV light penetration. This may then increase oxygen saturation.

Phoslock – Phosphorous is the main food source for algae. By reducing the nutrient input, algae do not have enough food to replicate.

Barley Straw Bales and Barley Straw Extract – Barley Straw works to suppress the future growth of algae.

Waterbac – Beneficial Bacteria helps to reduce excess nutrients in the water body which may lead to an algal bloom.