http://www.inspection.gc.ca/animals/.../1331908089467
Basicly, declare your animal, make sure its not a CITES animal or an animal on the susceptible species list. If you know what kind of fish youre bringing over, have some info on it printed out a head of time to prove scientific name/id. Clark's has those old style Tills that the receipt really just shows what you paid, not an item/animal name.