Kosher certification and use of a kosher symbol is provided by third party organizations that verify the food is produced in compliance with Jewish dietary laws.
To label your fish product as kosher, contact one of the third party organizations that will inspect your ingredient list, production facility and process. If compliant, they will issue a trademarked kosher symbol for use on your packaging.
Please note that the kosher certification process is independent from U.S. food safety and labeling laws. If a kosher symbol is used, it cannot interfere with federally required information on the food label.