I have entered ` as part of the namme in My Aquaria, and I have looked at the code behind the scenes, and I don't see a problem.
As you can see here:
http://www.planetcatfish.com/common/my_ ... &task=show
I have an aquarium called "mix`em".
Not sure what I'm doing different, so perhaps you can help out by trying again and recording exactly what steps you take, and what the error message is.
Edit: I also added a fish to the tank...
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Mats