There are restrictions. But you can't get a clear definition of what they are from customs. I have made numerous calls to Customs Canada when I lived in North Carolina but had my tank set up here in our Windsor home. There were some great deals I wanted to bring from my awesome lfs in NC to my tank in Canada.
I eventually just brought frags over the border, declaring that I had "core flags". If they asked me what a "core flag" was, I going to clarify that they were "coral frags" and see what their response was. But they didn't ask.
There aren't any customs officers on this site, are there?