Vice Mayor of Vientiane Mr Saithong Keoduangdy asked the officials to legalise the nine farms by that date when he visited the district early last month to give guidance on regulating illegal foreign workers in the district.
Mr Saithong also told officials that illegal fish farm operators who failed to present their business documents by that date would have their businesses seized starting March 1.
His instruction came after the government had given the illegal fish farmers a grace period within which to legalise their operations, but they had failed to do so.
Deputy Governor of Xaythany district, Ms Khamphay Latsamy, admitted that there had been complications in the legalisation process, and more time was required.
District officials on Wednesday submitted a document to the Mayor of Vientiane requesting further guidance on the issue.
Chinese nationals were reportedly operating 13 fish farms in the district, but only four could produce legal documents. Many of the illegal operators were reportedly using licences bearing the names of Lao people.
Vientiane is launching a pilot scheme to regulate illegal foreign workers to comply with the government's instructions on the issue.