Crustaceans · Palaemonidae
Harlequin shrimp
White shrimp with large coloured spots and petal-like flattened claws that feeds only on sea stars. It lives in pairs on Indo-Pacific reefs; in the aquarium you must be able to supply sea stars without interruption.
What it needs
Related species
Ancylomenes pedersoni
Range recommended by the sheet
Day to day
Acclimation: like all shrimp, it copes badly with sudden changes in temperature, pH or other water parameters. Drip-acclimate it for about one hour.
Before you buy: the real challenge is food. Plan a regular supply of sea stars: a medium-sized star feeds a pair for about a week, and leftovers must be removed so they do not pollute the tank. It can wipe out small Asterina stars, but you will then need to supply larger ones.
Setup and tankmates: keep it as a mated pair in a tank with moderate light. Every sea star in the tank (Linckia, Fromia, Nardoa…) is prey; in the aquarium it also eats sea urchins and brittle stars. It leaves fish and corals alone.
Sensitivities: like other invertebrates, it does not tolerate copper treatments or high nitrate. Keep iodine at a correct level so that moults go well. After a moult the shell stays soft for a while and it hides, because predators, and sometimes its own kind, may attack it.
Water: aim for 22 to 25.5 °C, a specific gravity of 1.023 to 1.025, pH 8.1 to 8.4 and 8 to 12 dKH.
In the wild it feeds exclusively on sea stars, preferably of the genera Fromia, Linckia and Nardoa, and also on the crown-of-thorns starfish. It starts at the tip of an arm and works its way to the central disc.
In the aquarium you must supply live sea stars: LiveAquaria mentions Asterias rubens for adults and Linckia for juveniles. A medium-sized star lasts a pair about a week; remove the leftovers. It also eats sea urchins and brittle stars.
Tank mates
In detail
Identification: about 5 cm, the male slightly smaller than the female, which also has coloured abdominal plates the male lacks. The body is cream or white with large spots; the claws and eyes are flattened, and petal-like antennules are used to smell out prey. Some authors split it into two species: H. picta from the central and eastern Pacific, with pinkish-purple spots edged in yellow, and H. elegans from the Indian Ocean and western Pacific, with browner spots edged in blue; in Hawaii it has purple and red spots. WoRMS treats H. elegans as a synonym of H. picta.
In the wild it lives on tropical coral reefs of the Indian and Pacific Oceans as far as Hawaii, from 1 to 20 m. Male and female live in pairs and forage together. It feeds exclusively on sea stars: it prefers small, sedentary species but also attacks the crown-of-thorns starfish, which it kills within a few days. It flips the sea star onto its back, pierces the skin with its claws and eats the tube feet and soft tissue up to the central disc; the star may shed the attacked arm but is often too badly wounded to survive. It eats sea urchins only when sea stars are lacking.
Reproduction: a female produces 100 to 5,000 eggs per season depending on conditions. It has spawned in captivity, but its highly specialised diet makes breeding very difficult. The species is not evaluated by the IUCN and not listed by CITES.
Status
Not evaluated (NE)
WoRMS
AphiaID 210554 · See on WoRMS (opens in a new tab)
Where this comes from
Ancylomenes pedersoni
Calcinus laevimanus
Lysmata amboinensis
Neopetrolisthes maculatus
Stenopus hispidus
Alpheus randalli
Calcinus elegans
Clibanarius tricolor
