Where to dive with seahorses

What they are

More than 45 seahorse species live in coastal waters worldwide. The smallest is about the size of a lima bean, while the largest can grow to more than a foot (about 30 cm) from head to tail tip. In a reproductive role reversal, it is the males that become pregnant.¹

Pygmy seahorses are tiny. Hippocampus bargibanti reaches a maximum height of about 24 mm according to Fishes of Australia, while the Australian Museum gives a length of 2 cm. It matches the colours of its host coral so closely that it is hard to see.^2,3

Where and when divers see them

Seahorses do well in seagrass beds, mangroves, estuaries and coral reefs. The pygmy seahorse H. bargibanti lives on coral reefs and reef slopes at 16 to 60 m, usually on gorgonian sea fans of the genus Muricella, across the tropical West Pacific.^1,2,3

Conservation status

The 2016 global IUCN Red List assessment of seahorses, led by Project Seahorse and the IUCN SSC Seahorse, Pipefish and Seadragon Specialist Group, found at least a third of the 42 species then recognised to be threatened. Two species were listed as Endangered, 12 as Vulnerable, mostly in East and Southeast Asia because of fishing pressure, and 17 as Data Deficient.⁴

The pygmy seahorse H. bargibanti is listed as Data Deficient on the 2010 IUCN Red List, according to Fishes of Australia. Four seahorse species found since 2016, three of them pygmy seahorses, still await a first assessment. National Geographic names overfishing, including bycatch, as the main threat to seahorses.^1,2,4

How to behave around them

The IUCN Seahorse, Pipefish and Seadragon Specialist Group publishes a tourism code of conduct for divers and snorkellers. Its main points are below.⁵

• Never touch a seahorse, and do not move, coax or force it to move.⁵
• Never capture, handle or remove one from its habitat.⁵
• Keep out of the animal's immediate space and limit time spent close to it.⁵
• Do not surround it with a group of more than four divers or snorkellers.⁵
• Flash photography is acceptable in moderation.⁵