Moss Balls in the Aquarium

If you're looking for an exciting new plant to add your tropical freshwater aquarium, you can't do much better than to find some moss balls. In fact, these unusual plants are so much fun that some aquarists keep them on their own, without fish! Considered a national treasure in their native Japan, they have taken the international aquarium hobby market by storm.

What are Moss Balls?

In Japanese mythology, moss balls were created from two lovers who ran away together, so they are a symbol of romance. People everywhere are fascinated by them because of the way they move around in the water, unanchored and independent of currents, chasing shafts of light. This can make them seem more like animals and plants.

In fact, moss balls are not true plants. They're a form of filamentous algae, but you won't need to worry about them infesting your tank. Not only do they maintain their spherical shape and stay roughly the same size (optimised for drawing nutrition from sunlight), but they use up the nutrients ordinary algae likes to feed on, thus helping to keep your aquarium walls clean.

Caring for Moss Balls

Despite having a sense for light, moss balls will not react to your fish or to you. Some fish like to nibble on them but this won't usually do them any serious harm. Sometimes the fish are looking for accumulated debris rather than the algae itself. You can even take moss balls out of the tank and handle them - gently - as long as you don't let them dry out.

Sometimes moss balls are attacked by other forms of algae which grow on their surfaces. If you notice any change in their colour, or if they behave abnormally, brush them gently with your fingertips to clear away any invading algae. This is usually sufficient to restore them to health.

Moss balls will thrive right across the range of temperatures suitable for keeping tropical fish, and they're not too sensitive to pH changes, but keeping an eye of them can help you detect any changes that might be problematic for your fish. The most important thing is to give them plenty of light, ideally shifting light so you can watch them move around.

Breeding Moss Balls

If you look after your moss balls well, you may be lucky enough to see them make more. Watch out for oddly shaped bulges in their sides. After these have been developing for a couple of days, you can gently squeeze around them and a new moss ball will bud off. Bear in mind that you may need to keep these smaller balls out of the way of hungry fish until they grow to full size.

Baby moss balls are shaggier than their parents, so need to be cleaned more often and more carefully. If they leak dirt when you handle them, don't try to clean it out - they need it to bind themselves together.

When you purchase moss balls, be careful to make sure that you're getting the real thing. Some unscrupulous dealers grow algae on Styrofoam balls and pass these off as moss balls. You can identify the fake ones by the way they float at the top instead of moving around.

Moss balls are great fun and really add character to your tank. Though they may surprise your fish at first, they're very little trouble to look after, and they add a new dimension to aquarium keeping.