Customers visiting the Marlex will now have to wear face coverings when they enter, exit or move through the bar.
In a Facebook post on Sunday evening, the owners announced that all of their customers will have to wear face coverings when they are not seated at their tables.
“Please have face coverings on when entering or departing or when visiting the toilets,” the bar owners asked.
First Minister Nicola Sturgeon announced a stricter set of rules for pubs and restaurants on Friday, after breaches in lockdown restrictions on the mainland.
Pubs now have a legal obligation to collect and keep customer details, though Lerwick bars such as the Marlex and The Lounge have already been taking customer names and contact numbers in line with the Scottish government guidance.