The Moss Ball

Moss balls

The Moss Ball is an adorable addition to an aquarium requiring minimal maintenance. In this article, we’ll discuss the unique characteristics of this plant, best care practices for aquarists, and potential issues concerning browning.

The Moss Ball, scientifically known as Aegagropila linnaei, is an alga that grows in the shape of a ball. It is primarily found in Japan and Northern Europe and is believed to be a bearer of good fortune according to Japanese culture. In 1898, a Japanese botanist, Tatsuhiko Kawakami, granted these species the name “Marimo.” The Japanese term has, however, proved to be a misnomer since “mari” translates to a ball and “mo” to algae in English. The adverse inferences from the algae have led to these algae balls being called moss. This naming is, therefore, inaccurate, given the balls consist of algae, not moss.

Moss balls are algae filaments that grow into balls. The filaments radiate from the center of the ball and do not grow kernels.

In the wild, the species is primarily found in Japan and Northern Europe, typically in areas that feature glaciers. Moss balls thrive in lakes characterized by deprivation of biological activities. They also grow in wet areas with fair or abundant amounts of calcium.

The round shape of moss balls is attributed to the tidal action subjected to them by water. The balls grow gradually, about 5mm annually, with the maximum size achieved depending on their environment. They typically reach spans of 2-5 inches in aquariums or 8-12 inches in the wild.

Moss balls can be a great addition to an aquarium. They require minimal maintenance, adapt quickly to different conditions, and don’t generate dead matter. They are filter feeders, which means they help clear waste in the aquarium.

Besides being great for aquariums, some grow moss balls in glass containers, such as bowls, vases, and bottles.


Water Requirements

Wild moss balls exist in cold, dark waters, where the waves slowly turn them to expose all sides to the light. They thrive best in low light, low temperatures, and high mineral content.

The water should be changed every two weeks to dispose of debris, but more often in the summer and less during winter. When growing in an environment with temperatures ranging from 77°F (25°C) or above, moss balls can be kept in a refrigerator for up to 48 hours.

Amount of Light Needed

Moss balls typically develop at the bed of lakes, where high-intensity lighting is absent. They can undertake photosynthesis with standard household lighting, but indirect sunlight is also an option. They should never be exposed to direct sunlight because they are only adapted for low light conditions.

When exposed to high-intensity light, moss balls may exhibit brown spots. Most aquarium lamps provide adequate lighting for the survival of moss balls. If these balls remain stationary for extended periods, keepers should rotate them to facilitate light reception on all sides.

Can Marimo Survive Outside of Water?

Yes! Marimo moss balls can survive without water if kept inside a plastic bag or closed jar. However, they should be kept moist since they die when completely dried out.

Keeping Marimo Shape Round

To ensure moss balls retain their round shape, gently agitate the water they are growing in. The simulated tidal action is essential in creating and maintaining their round shape. Also, gently rolling the moss balls when cleaning them will help them round up.


High water temperatures, exposure to high-intensity lighting, and poor water quality can cause browning in moss balls. Moss balls recover their green color by being moved to environments with cooler conditions and less lighting.

Moss balls can add a lovely green accent to your aquarium. Consider moss balls for aquariums for their relatively low maintenance and adorable appearance.

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