Fish

Common (estuary) seahorse

Hippocampus kuda

A seahorse holds a blade of seagrass with its tail and barely moves. You find it by looking slowly, and a sighting is never promised.

VulnerableIn 25 Atlas countries

Vulnerable (IUCN, 2012) means it is at high risk of extinction in the wild.

Estuary seahorse with textured orange skin on dark sand — Photo: Pauline Walsh Jacobson, iNaturalist, CC BY

Estuary seahorse resting on a sandy seabed — Photo: Piotr Lukasik, iNaturalist, CC BY

Estuary seahorse among seagrass in Hawaii — Photo: Robin White, iNaturalist, CC BY

Orange estuary seahorse clinging to a rock — Photo: Roger Rittmaster, iNaturalist, CC BY

Yellow-green estuary seahorse among seagrass on sand — Photo: Dominik Maximilián Ramík, iNaturalist, CC BY

Estuary seahorse on sand beside a sponge — Photo: portioid, iNaturalist, CC BY

Estuary seahorse holding onto a sunken structure — Photo: Ioannis Magouras, iNaturalist, CC BY

Brown estuary seahorse on sand among seagrass — Photo: Gregor Bailar, iNaturalist, CC BY

Photos show the species, not always the places on this page.

Length

Usually about 7 to 17 cm (3 to 7 in) tall; measured stretched out, the largest recorded is about 30 cm (12 in)

Weight

Only a few grams; adults in one Indian study weighed about 5 to 19 g (0.2 to 0.7 oz)

Next to a person

Palm-sized, about as big as a closed adult fist

What it eats

Small crustaceans and other tiny plankton, sucked in through its tube-shaped snout. It does not eat seagrass.

Around people

Harmless

How it lives

This seahorse holds on to seagrass, mangrove roots or debris with its tail. It is a poor swimmer and relies on camouflage to stay safe, and its colour can change to match its surroundings. It sucks up small crustaceans and plankton through its tube-shaped snout. The male carries the eggs in a pouch for about 20 to 28 days before the young swim out.

Where it goes

It does not migrate. It usually lives in shallow water from 0 to 8 m, but has been recorded deeper than 50 m. Adults are often seen in pairs.

We only draw a journey on the map when scientists have tracked it or clearly documented it. For this animal we have not found one yet.

Populations

It lives across the Indo-Pacific, from southern Africa and the Red Sea to Hawaii and French Polynesia. It is listed as Vulnerable because numbers are believed to have fallen by 30% or more, from fishing for trade, bycatch and habitat loss. A 2001 study recorded this species in Lombok, alongside another seahorse, Hippocampus barbouri.

Meet it respectfully

Look only. Never touch a seahorse or lift it off whatever it is holding, never chase it, and keep good buoyancy so you do not damage the seagrass. Keep bright lights and flash to a minimum and follow your guide. Never take one as a souvenir: international trade in seahorses is controlled under CITES, and Indonesia restricts wild export.

Fun fact

Tap the bulb to light it up.

Sources for this page

Facts checked 26 September 2026. Photos: Unsplash licence, or Creative Commons as shown on each photo.

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