Prime Minister Frank Bainimarama says the latest case came after a batch of 25 samples were tested overnight.
He said the confirmed cases was the husband of an existing patient from Lautoka, someone who had done a Zumba exercise class with Fiji's first coronavirus case.
Mr Bainimarama said the 33-year-old man was now in isolation.
The man represented the sixth confirmed transmission that could be traced back to Fiji's first case, a flight attendant who had returned from overseas.
The government said all 15 patients remained in stable condition.