Inhabits harbours and sheltered coastal bays (3). They can be found amongst algae, seagrasses and around rocky reefs in fairly shallow water. In deeper water they typically attach to sponges (2). Unlike most seahorse species, the big-belly seahorse is a relatively strong swimmer and has been known to swim over hundreds of meters in the course of a day (11). Adults are also known to occur in open water and to raft on algal rafts and seagrass. Artificial structures appear to be important habitats for this species - in particular jetties, nets and salmon cages (10).