If you have a problem with slimy, dark green/blue algae in your aquarium it is unlikely that fish will eat it. Or if you have algae eaters that cannot keep up with the algae growth, it might be worth looking at what might be causing it to grow.
Things to consider:
1) Aquarium Lighting - make sure that your tank is not in direct sunlight. Also make sure that you only have your aquarium light on for about 7-8 hours a day.
2) Lots of live plants will also help to reduce algae growth. Plants feed on the same nutrients out of the water that the algae would feed on, therefore inhibiting growth.
3) Make sure that you are not over feeding. Once a day is plenty, missing one day a week will also help to make sure that your fish are not being overfed.
4) Test your aquarium water - High levels of Phosphate in your water will encourage algae growth. This can be found in many fish foods but occasionally in tap water too. If the levels get too high you can buy products that will remove the Phosphates from your water.
5) You may need to treat the algae with a chemical treatment. Make sure that you get the right one for the type of algae that you have in your aquarium. We are always happy to give advice on how to get rid of the algae in your aquarium.
Byrkley Aquatics - Rangemore