This page explains briefly what to do about algae growing in your fish's home. More importantly there is also information about why algae is growing in your fish's home.
 
"Your fish's home" might be an aquarium, a fish bowl, or a pond. The comments on this page apply to all three types of fish homes.

1. A Short Answer
If the water in your fish's home is green, then algae is growing the water, which shows that the water contains too much dissolved fish waste. You should change some of the water in your fish's home every day, until the water in your fish's home is clear again.

How much water should you change? Don't overreact and change too much water at one time. Change 20% of the water once each day until the green is gone, then change 20% of the water twice a week.

Don't change more than 20% of the water in one day, unless you have a catastrophe, and green algae is not a catastrophe. Click here for information about changing water in your fish's home. 

Thank you Dan for your explanation. There are several types of algae, that grow in fish's homes. Some types of algae float and multiply in the water. Other types of algae grow on objects such as the rocks, ornaments, gravel, plants, and the glass in your fish's home.

All Algae is not Green. There is also black algae, brown algae, red algae, and several other color variations. Everything written on the this page about green algae applies to the other color varieties of algae too.

3. Why is Algae Growing in My Fish's Home?
Algae needs water, light, and nutrients. If your fish's home has too much algae, we know your water is getting lots of light and has lots of nutrients dissolved in it. Where did the nutrients come from? Fish eat food and produce waste that is an excellent nutrient for algae.

4. How Do I Get Rid of the Algae?
There are four approaches to getting rid of algae. Get some fish to eat it, poison the algae with chemicals, reduce the amount of light, and starve the algae by reducing the amount of nutrients in the water.

Algae Eating Fish such as Plecostomus Catfish and Siamese Algae Eaters are both good aquarium fishes that will eat some types of algae growing on the objects in your fish's home. But they will usually not eat all the algae, and we don't have a fish available that will filter out the algae that grows in water and makes the water green. Most aquarist enjoy having one or both of these types of fish, but an algae eating fish usually won't solve an algae problem.

Plecostomus Catfish do not eat all types of algae, and you may have a type of algae that your Plecostomus does not like to eat. Do not depend on a Plecostomus Catfish to solve your algae problem.