Algae in Marimo Aquarium

Maybe aquarium is too lavish a word to describe where my Marimo lives, but he doesn’t seem to know or care about that. Maximus, as I’ve named him, was living rather contently in his little jar on my desk until late last spring. That’s when the position of the sun shifted in the sky and the morning sun began to shine through the window and hit the desk on the other side of the room. Because I was busy with the Amaryllis bulbs and seed starting I didn’t really pay attention to my Japanese “moss ball” and where it was sitting in relation to the sun. If you’ve ever kept an aquarium you know where this is going, right? Algae!

Water and sunlight is a breeding ground for algae and it is mostly unavoidable. One day my Marimo was living contently in his jar and the next day he was covered in algae and it enveloped the inside of the aquarium too. It looked really bad. There is no single cure for algae in aquariums because there are a variety of algae that attack aquariums. I was tempted to get some drops from a pet supply store then I remembered that Marimos are actually fresh water algae, Cladophora aegagropila, and that any chemical treatment might also affected Maximus.

So I did the only other thing I could think of and moved the Marimo to the hallway outside my room where very little natural light would reach it. Since the high light level was causing the buildup of brown algae in the aquarium, I figured if I starved it the brown algae would die and Maximus would survive. It has taken a few months of being in a lower light environment and frequent water changes, but it seems like I’ve starved the algae. What you see above is the debris of the algae as it has slowly died, it no longer envelopes Maximus.

Although he does look a little worse than when I first posted pictures of him here on the garden blog in 2008. He seems to be on the verge of breaking apart, which isn’t really a problem since they propagate vegetatively by breaking off clumps or when water currents bash them into things like driftwood, vegetation, and stones below water.

Marimos are mistakenly referred to as “moss balls” but they’re really a species of filamentous algae. If you’re looking for a fun “plant” to add to your indoor garden collection I highly recommend buying and growing a Marimo. They’re interesting little creatures that may not do much at first glance, but once you’ve had one around for a while you’ll see that it is very much a living thing. Sometimes Maximus floats and even in his cramped aquarium he moves around, either inching towards the light from the windows during cloudy days, or away from the light on very bright days.