The island contains a flood pond to support the local wildlife during the winter months, but no buildings or services.
The listing agency said Barlocco Island is part of the Borgue Coast Site of Special Scientific Interest, which means its natural areas are protected by the British government.
Listing agent David Corrie said any buyer seeking to bring power to the island would not be able to connect to any energy grid, but they would likely be able to install solar panels or other off-grid technologies.
Corrie told The New York Times the island "has been renowned for centuries as a place of unique landscape and natural light, a feature which attracted many artists to the area in the 19th and 20th centuries."
Galbraith Group said the island can be reached on foot during low tide, but a boat would be required during high tide.
"There's still a very romantic sentiment attached to owning your very own Scottish private island, where you can escape the hustle and bustle of everyday life and enjoy some peace and tranquillity in the most beautiful scenery around," Aaron Edgar of Galbraith said on the listing agency's website.
"The pebble beach is a delight and the perfect base to explore the island, partake in some cold water swimming or to anchor a boat and enjoy a waterside picnic," he said.