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Neomeris sp 01.jpg
Neomeris sp., Spindle Weed


Algae are a loose collection of photosynthetic organisms. They all have chlorophyll a and other photosythetic pigments and they all produce oxygen. While algae are plant-like, they are no longer considered part of Kingdom Plantae, with most algal groups considered protists (Kingdom Protista). The exception to this are the cyanobacteria which are procaryotic.

The word "algae" is plural and the singular is "alga".

Algae is typically divided into two general types of hobbyists, Macro and Micro. Typically macro algae is encouraged for nutrient export, appearance or for feeding of herbivores such as tangs. And micro algae is the basis for the algae turf scrubber filtration method.

For identification, see Image Identification Key - Algae


Caulerpa taxifolia, macro algae that is now illegal to be in possession of in NSW, Victoria, Tasmania, and South Australia due to it's potential weed impact.

Other Algae


Refer to Controlling Problem Algae






I am getting a red slimey algae on my substrate and rocks. What is this stuff and what can I do to get rid of it?

This is cyanobacteria. Cyanobacteria is a photosynthetic bacteria which colonises much like many types of algae, it can spread very quickly. Cyanobacteria has a few different forms in the marine aquarium; dark blue/green, velvet red, and brown. It is thought that cyanobacteria are among one of the oldest known lifeforms on earth, showing fossil records of up to 3.5MYA. You may have seen on the news or first person that some parts of the ocean looking completely red, or blue green, it is a major problem for our environment, however this only happens when there is a huge nutrient resource for the cyanobacteria to grow. Their main source of nutrients in an aquarium are nitrates and phosphates, and will thrive with slightly higher than normal levels in your tank. It is not desirable to have cyanobacteria in your aquarium as nothing will eat it, and it will continue to grow if the proper measures aren't taken to remove it. Some methods of treating cyanobacteria include:

  • Increasing water flow on the particular area that it is growing; It will find it harder grow in high current areas.
  • Large water changes; removes the nutrient source.
  • Increase skimming; skimmers are often an effective way of removing some of it's nutrient sources. Prevents some of it's nutrient sources from growing due to the removal of Dissolved Organic Compounds (DOCs)
  • Reduce the amount of time the lights are on.
  • If you have no light dependant animals (photosynthetic), remove the light source completely until the bacteria appears to have subsided
  • Reduce nutrient input; feed your fish sparingly. Cyano loves fish poo.
  • Siphoning the cyanobacteria out. This is not recommended if you have a deep sand bed (DSB)

Often a combination of a couple of methods is the quickest and most effective way of removing it.

I have noticed algae seems to be taking over my tank! What critters can I use to get rid of it?

Depending on the type of algae; macro, micro, or cyanobacteria, you may have success with the following:

  • Various Hermit crabs. Depending on the species, some hermit crabs may be specialised grazers, some may eat filamentous algae, while others may eat macroalgae.
  • Various snail species; Turbo, Trochus, Tectus, Astrea and Australium. Some snails may eat macroalgae as well as micro algae, however most will only eat the latter. One species of cowry in particular is a noted algae eater, that is Cypraea erosa. Other cowries are not suited for aquariums as their diet consists mostly of corals, other snails, and sponges.
  • Lawnmower Blenny: Salarias fasciatus. Mouth is lined with hundreds of tiny rasping teeth. This blenny will decimate most filamentous algae, though is very unlikely to impact on macroalgae populations.
  • Rabbitfish or foxfaces: Family Siganidae. These omnivorous fish graze heavily on both macro and micro algae species.
  • Tangs or surgeonfish: Family Acanthuridae. Only recommended for slightly larger tanks. Constant grazers, will control many types of algae.
  • Urchins, various species, notably Tripneustes and Mespilia sp. Urchins will eat a variety of algae, ranging from micro algae, macro algae, to coralline algae.

You are very unlikely to have any success in ridding your tank of cyanobacteria with the animals mentioned above. Some blennies and snails may impact a little, however, it is an extremely fast growing alga that is generally an undesired food for most animals.