Marimo Moss Ball

Aegagropila linnaei

A green velvet ball that is not a plant at all but a colony of algae, rolled into shape by the waves of cold northern lakes. The one alga in the hobby that is kept on purpose.

Light: low
Difficulty: easy
Height: 3 – 10 cm (1.2 – 3.9 in)
Temperature: 4 – 28 °C (39 – 82 °F)

Leaf colour: green
Plant type: alga
Growth rate: very slow
CO₂ demand: low
Tolerates light: low – high
pH: 6 – 8
Carbonate hardness: 2 – 18 °dKH
General hardness: 9 – 30 °dGH
Placement: midground, foreground
Propagation: division, daughter plants
Grows emersed: no

Appearance

A dense sphere 3–10 cm across, soft and velvety, of an even deep green. It grows extremely slowly — a few millimetres a year.

Keeping

Simple, with one condition: cool water. It comes from northern lakes, and in a warm tropical tank it slowly falls apart. Bright light is unnecessary and even harmful. Turn the ball over now and then, or the side lying on the substrate goes pale and the shape is lost.

Placement

On the substrate in the front or middle of the tank, where the sphere is visible. Shrimp pick over it constantly, which is why shrimp keepers buy it.

Propagation

Divide it: cut or pull the ball into pieces and roll each piece gently in your hands; over months every piece rounds itself off again. A piece tied to a stone or a root spreads into a green mat instead.

Water conditions match

The water suits 856 of 1249 species in the catalogue — these are the ones people look up most often.

Swordtail Guppies Cobra Guppy Blood Red Molly Butterflyfish Red Zebra Cichlid Julii Corydoras Red-finned Parotocinclus Gastromyzon monticola Egg-shaped Goldfish Flame Tetra Gardner's Killifish African Tetra Kenyi Cichlid Cuckoo Catfish Golden Swordtail Common Zacco Labeo Bicolor Gambusia Flying barb Gastromyzon scitulus Albino Zebra Danio Geophagus Brokopondo Zebra Mbuna Homaloptera bilineata

Will eat this plant

These species damage plants, especially when their diet is short of vegetable food.

Bengal Loach Zebra Loach Burmese Border Loach Spined Loach Marbled Headstander Pellegrin's Leporinus Leporinus striatus False Black Tetra Common Metynnis Mylossoma duriventre Red Whiptail Catfish Molly sphenops Balloon Molly Lyretail Molly Marble Molly Hi-Fin Platy Hawaii Platy Blue Platy Pintail Platy Black Platy Chocolate Molly Moonlight Gourami Melanotaenia parva

Will uproot it

These species dig through the substrate and pull rooted plants out.

Marble Loach Peacock Eel Forktail Loach Guntea Loach Long-nosed Loach Horseface Loach Pearlscale Black Moor Goldfish Shubunkin Painted Pleco Featherfin Synodontis Reddish Mystus Catfish Blue Acara Aulonocara maylandi Aulonocara multicolor Aulonocara Orchid Pearlscale Cichlid Pearl Cichlid Redbelly Cichlid Red-spotted Cichlid Chuco godmanni Haplochromis philander Red Chromide Jack Dempsey cichlid

Matching water does not mean the fish will leave the plant alone.

Scientific and other names, conservation status

Other scientific names: Conferva aegagropila Linnaeus, Cladophora aegagropila (Linnaeus) Trevisan, Cladophora aegagropila var. linnaei (Kutzing) Rabenhorst, Cladophora sauteri (Nees von Esenbeck ex Kutzing) Kutzing, ? sauteri, Aegagropila bulnheimii, Aegagropila holsatica, Aegagropila sauteri, Cladophora aegagropila, Cladophora aegagropila brownii, Cladophora aegagropila bulnheimii, Cladophora aegagropila daldinii, Cladophora aegagropila holsatica, Cladophora aegagropila martensii, Cladophora aegagropila muscoides, Cladophora aegagropila sauteri, Cladophora aegagropila thermalis, Cladophora holsatica, Cladophora koktschetavensis, Cladophora sauteri, Cladophora yuennanensis, Conferva aegagropila
Aegagropila linnaei: Kutzing
Family: Pithophoraceae