What fish can I add to control filamentous algae?

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What natural controls can you add to your aquarium to deal with growths of filamentous algae in your community tank? Dr Heok Hee Ng has some suggestions.

Filamentous algae is perhaps one of the easier types of algae to control.

Several fish species can be considered, depending on the composition of your community tank. One prime candidate among the lage eaters is the American flagfish (Jordanella floridae) which grows to about 6cm/2.4”. Mollies (Poecilia sphenops/P. latipinna/P. velifera) are similarly suitable, if slightly larger, candidates.

Also consider algae-eating cyprinids. These include Siamese algae eaters (Crossocheilus spp.), which usually reach 15cm/6” in size, or members of the genus Garra (such as the Panda garra, G. flavatra), many of which reach the same size as Siamese algae eaters, although a few reach 25cm/10”.

Algae-eating cyprinids generally require fairly well-oxygenated water and are sensitive to high temperatures, so try to keep water below 26°C/79°F.

Avoid getting standard algae-eating plecs such as Bristlenoses (Ancistrus spp.) or Otocinclus spp., as these eat very little if any filamentous algae.

This article was first published in the December 2009 issue of Practical Fishkeeping magazine. It may not be reproduced without written permission.