
The Upside-down Pipefish can be recognised by its very large caudal fin with incised membrane, and raised body ridges along the body.
There are two distinct forms. The east coast form (pictured) is recorded from northern to southern New South Wales. It is dark brown to black with or without pale blotches. The south coast form is a mottled yellow-brown with light markings and a smaller caudal fin. It is recorded from the central coast of Victoria to southern Western Australia.
The Upside-down Pipefish grows to 10 cm in length.
It lives in protected bays and estuaries down to a depth of about 20m, where it is usually seen in pairs in caves and under ledges. It is often seen swimming upside-down, hence the common name.
Heraldia nocturna was described by Australian Museum Research Fellow, Dr J. Paxton in 1975. The holotype is registered in the Australian Museum Fish Collection (AMS I.17328-001).