Well, here is an answer from somebody who has imported thousands of boxes of fish from the US (and other places), is quite familiar with customs, and lives in Calgary.
Shipped via an airline (ship either afternoon or in the evening, so that it will arrive during business hours), the box of fish should arrive in about 6-14 hours (make certain that the fish are packed with pure oxygen in the bags...or in breather bags...in a proper styro fish shipping box, and use a 20+ hour heat pack), depending on where it is coming from and how direct the flight is. Upon arrival, you simply take the paperwork to customs for them to clear. Customs costs are minimal for personal shipments, and clearing should take about 60-90 minutes at most. And yes, its all perfectly legal, although the shipping will probably run about $100.