It's a small fish which can reach a maximal length of 14 cm.
Native in the tropical waters of the central Indo-Pacific. Doryrhamphus janssi is a cleaner fish specialised in small fish, they usually work in couple. It is ovoviviparous and like for the seahorse, the male carries the eggs in a brood pouch.
It belongs to the family og so called flagtail pipefish. Name comes from habit of flashing the distinctly patterned tails during courtship. The specific name honours Edwin Janns Jr., a Los Angeles property developer who had a keen interest in marine biology.