I suggest anyone contemplating importing any fish look up CFIA's AIRS. You can go species, location and use specific to your case. For personal use as an example of ornamental goldfish from thailand, all that's required is the following:

"When importing pet aquatic animals, the owner is required to complete and provide the Importer's Declaration of Ownership for Pet Aquatic Animals Form at the point of entry. This form can be found at: Forms Catalogue - Canadian Food Inspection Agency

For more information on Pet Aquatic Animal Exemptions, please refer to : http://www.inspection.gc.ca/animals/aquatic-animals/imports/aquatic-animals/eng/1331906471842/1331908089467"