One of the largest seahorses, deep-bodied and often pale, on jetty pylons and sponge in the temperate south.
To 35 cm, which makes it the largest seahorse in Australia and one of the largest anywhere. It has more dorsal fin rays and more tail rings than any other seahorse. Males have a very large distended belly; females have a compressed belly with a keel down the middle. The crown on the head is low and triangular, and there are fleshy filaments on the head. The colour runs from white through mottled yellow, reddish and brown, with darker blotches.
Size alone separates it from the other Australian seahorses, backed up by the pot-bellied profile of the male.
It is nocturnal. It lives on rocky reef, kelp, jetty piles, sponges and large seaweed, and in big low-tide rock pools, and it is strongly associated with artificial structure — piles and nets are where divers most often find it. It has been recorded rafting on floating seagrass. The male carries the eggs for about four weeks.
It is a temperate fish, from northern New South Wales round the southern coast to South Australia and Tasmania, and also in New Zealand. It does not occur on the Great Barrier Reef. Like every seahorse it is listed on Appendix II of CITES, and it is bred commercially.
Ratings are per location: 1 means found on most dives that look for it, 5 means a handful of records. Where enough dives have been logged the figure is calculated from them; otherwise it is an editorial estimate, and says so. We publish habitat and destination, not the dive site.