Marimo moss balls, scientifically known as Aegagropila linnaei, are a unique form of filamentous green algae that naturally grow into spherical shapes. They originate from cold, freshwater lakes in specific regions globally, including Japan, Iceland, Scotland, and Estonia. Gentle water currents in these lakes naturally form and maintain their distinct round, velvety appearance. Often called “pets” due to minimal care and unique presence, these living algae spheres make fascinating, long-lasting home additions.
Daily and Weekly Care
Proper water conditions are fundamental for Marimo moss balls. They thrive in clean, fresh water, ideally dechlorinated tap, filtered, or bottled spring water. Change water every one to two weeks to prevent stagnation, more frequently in warmer months. Replace about 50% of the water during changes, adjusting for other tank inhabitants.
Optimal light conditions are important. As low-light organisms naturally residing at lake bottoms, they prefer indirect or ambient light. Direct sunlight is harmful, causing browning or bleaching. Four to eight hours of low to moderate light daily is sufficient for photosynthesis.
Maintain an appropriate temperature range. They prefer cooler water, ideally 59°F to 77°F (15°C to 25°C). Temperatures above 78°F (25.5°C) cause distress, leading to browning, floating, or decay. During warmer periods, a short “vacation” in the refrigerator (up to 24 hours) can help cool them.
Routine cleaning maintains a Marimo’s shape and cleanliness. During water changes, gently remove and rinse under cool, dechlorinated water. Lightly squeezing releases trapped debris or air bubbles. Gently rolling the moss ball between palms mimics natural wave action, preserving its spherical form.
Addressing Common Problems
Discoloration, like browning or yellowing, indicates environmental stress. Too much direct light or warm water are common causes. If browning occurs, relocate to a cooler spot with indirect light and ensure regular water changes to restore color. Trimming severely affected brown areas with sterilized scissors encourages new growth.
Unwanted algae on the Marimo’s surface can be a concern. While Marimo is algae, other species can grow on it, especially with too much light or excess nutrients. Gently rinsing and manually removing foreign algae keeps it clean. Reducing light exposure and consistent water changes prevent further algae proliferation.
Structural issues, like flattening or falling apart, result from lack of movement or poor water conditions. Lake currents continuously roll them in their natural habitat, maintaining roundness. To counteract this, regularly roll the moss ball gently during water changes to retain its spherical shape. Consistent water quality and avoiding rough handling maintain structural integrity.
Ensuring Long-Term Health
Choosing an ideal placement contributes to long-term health. They thrive in standalone containers like glass jars or vases, or in aquariums. In aquariums, they are compatible with most fish, except goldfish or some plecos that might eat or damage them. Marimo absorb nitrates and provide oxygen, benefiting the aquatic environment.
Marimo moss balls grow slowly, typically expanding about 5 millimeters per year. Despite slow growth, they boast impressive longevity, living 100 to 200 years in optimal conditions. This makes them a unique, enduring addition, potentially passed down through generations.
For larger Marimo, dividing them can maintain health or propagate new ones. If a moss ball grows significantly or appears to be breaking apart, gently tear it into smaller pieces. Each piece can then be rolled into a new sphere to grow independently. This process is not routine care but a way to manage growth or create additional moss balls.