i've read that a mandarin in the wild needs like 2 acres to roam around and feed to keep it healthy (that is without a fresh supply of copepods added to the tank, which i think might be hard to do in edmonton)
if i can find the article i will post it.
i can't find the article, but here is a neat think on mandarins....
http://www.melevsreef.com/mandarin_diner.html