I wouldn't place any fish in your tank. If you can't catch the fish, and the isopod(s) breed (and they will, like roaches!), you'll be in deep detritus.

Chances are, if you have one, your have more.
According to Dr.
Ron Shimek,
cirolanids only eat live fish. They live in the sand, and are nocturnal hunters. It will take about three months to starve them out.
If you search the UBB archives at reefs.org, you will find a few posts by Doc Ron on this very subject.
I feel for you man. I'm going thru the same thing. Four months with no fish, and I haven't seen a single one. Thankfully it's a new tank setup, and I had already planned on adding fish last.
Good luck.
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Jim Fox
http://www.nycas.com/jfox
In the sea of life, you're just a minnow...you live your life, insecure...