U.S. citizens wishing to marry a Mauritian citizen are encouraged to contact the Mauritian Civil Office prior to coming to Mauritius. Check their website.
Please note the Civil Office requires a police/criminal record (locally called a morality certificate) from the United States.  As the U.S. Embassy is unable to provide police records, American citizens have the choice of either swearing an affidavit before the Consular officer and paying a US $50 notarial fee or requesting a police record from their local police department in the United States.