The full-sized seahorse of muck sites, holding a single holdfast for weeks.
A seahorse to about 17 cm, smooth-bodied with low rounded tubercles rather than spines, a deep head and a low coronet. Colour ranges from black and dark brown through olive to a strong yellow or orange, often with fine dark speckling, and the same individual will change over days. Hippocampus kuda has long been used as a catch-all name for several similar smooth seahorses across the Indo-Pacific and the species boundaries are still being revised; a smooth full-sized seahorse on Indonesian silt is usually reported under this name and that is a convention rather than a certainty.
Anchors by the tail to weed, a rope, a discarded net or a piece of rubbish and will hold the same holdfast for weeks, which is why guides can take divers back to the same animal repeatedly. Pairs occupy overlapping ground and greet each other daily. Males brood the eggs in an abdominal pouch and give birth to free-swimming young. Recorded from the shallows to about 20 m. Rotating an animal on its holdfast for a better angle is the commonest bad habit around this species and it is worth not acquiring.
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.