Editing Rainbow trout (section)

====Didymo====
{{nowrap|''[[Didymosphenia geminata]]''}}, commonly known as didymo or rock snot, is a species of [[diatom]] that produces nuisance growths in freshwater rivers and streams with consistently cold water temperatures.<ref name=dpiw-tassie>{{cite web | url=http://dpipwe.tas.gov.au/biosecurity/aquatic-pests-and-diseases/aquatic-biosecurity-threats/didymo-%28rock-snot%29 | title=DPIPWE - Didymo (Rock Snot) | publisher=Tasmania Department of Primary Industries, Parks, Water and Environment | access-date=2014-08-12 | url-status=dead | archive-url=https://web.archive.org/web/20150308142725/http://dpipwe.tas.gov.au/biosecurity/aquatic-pests-and-diseases/aquatic-biosecurity-threats/didymo-(rock-snot) | archive-date=2015-03-08 }}</ref> In New Zealand, invasive didymo can form large mats on the bottom of rivers and streams in late winter. It is not considered a significant human health risk, but it can affect stream habitats and sources of food for fish, including rainbow trout, and make recreational activities unpleasant.<ref name="biosec-nz">{{cite web |url=http://www.biosecurity.govt.nz/faq/term/907/didymo-11.htm |title=Is Didymo an Exotic Species? |access-date=2013-12-01 |last=Biosecurity New Zealand |date=August 2007 |publisher=Biosecurity New Zealand |archive-url=https://web.archive.org/web/20131203005603/http://www.biosecurity.govt.nz/faq/term/907/didymo-11.htm |archive-date=2013-12-03 |url-status=dead }}</ref> Even though it is native in North America, it is considered a nuisance organism or invasive species.<ref>{{cite web |url=https://www.invasivespeciesinfo.gov/profile/didymo |title=Invasive Aquatic Species-Didymo |publisher=U.S. Department of Agriculture |access-date=2013-12-16}}</ref>