The IUCN Red List classifies Common seadragon as a species close to extinction. This species is widespread at depths ranging from 3 to 50 meters along the southern coast of Australia, approximately between Port Stephens, New South Wales and Geraldton, Western Australia, as well as along the coasts of Tasmania.
It is a fish similar to the hippocampus, characterized by the leaf-like protuberances that serve to camouflage it among aquatic plants. A similar species with even more prominent mimetic protrusions is the Leaf Dragon or Phycodurus eques.
The average length of this fish is about 46 cm. Mating in captivity is quite rare because researchers have yet to understand what biological or environmental factors are that drive them to reproduce. In captivity, the survival rate of the common sea dragon is around 60%.
The Aquarium of the Pacific in Long Beach, California and the Melbourne Aquarium in Australia are the only facilities in the world to have successfully bred the common sea dragon in captivity. Since June 2008, the Georgia Aquarium in Atlanta has a fruitful sea dragon and it is assumed that the young will be born by mid-July.
Captive breeding programs are in place for the weedy seadragon, headed up by Sea Life Melbourne Aquarium.
The dragon has been difficult to breed in captivity, though in 2015 research observing the creatures in the wild and trying to replicate the conditions in captivity had researchers making changes to the light, water temperature and water flow proving to be key.
In December 2015 the Melbourne aquarium hatched eggs and the aquarium's weedy seadragon population significantly increased. The aquarium reported in March 2016 that 45 fry were still going strong at 95% survival rate. Monitoring of populations may provide indications of local water quality and seadragons could also become an important 'flagship' species for the often-overlooked richness of the unique flora and fauna of Australia's south coast.
It is illegal to take or export these species in most of the states within which they occur. A database of seadragon sightings, known as Dragon Search has been established with support from the Marine Life Society of South Australia Inc.
The loss of suitable seagrass beds and loss of canopy seaweed from inshore rock reefs, coupled with natural history traits that make them poor dispersers, put the future of seadragon populations at risk. This species is not at present a victim of bycatch or a target of trade in traditional Chinese medicine, two activities which are currently a threat to many related seahorse and pipefish populations.
While the common seadragon is a desired species in the international aquarium trade, the volume of wild-caught individuals is small and therefore not currently a major threat. Instead, habitat loss and degradation due to human activities and pollution threaten common seadragons most.