RAINBOW ARMATUM CRAB / CARDISOMA ARMATUM – 彩虹蟹

Cardisoma armatum are more commonly known as Rainbow Crabs, Patriot Crabs, Tricolor Crabs, Moon Crabs or Soapdish Crabs. Rainbow Crabs are a popular group of semi-terrestrial crabs. They are hardy and easy to care for, making them a great choice for beginner aquarists. Rainbow Crabs are land crabs that originate from the West Coast of Africa. They can be found along the coastal regions in the river deltas and other brackish areas, building homes near sources of fresh or seawater. Their homes are burrows of sand that grow deeper and more complex as they age. Though in nature they can build deep colonies of tunnels, in captivity male Rainbow Crabs grow territorial in the presence of other male crabs.

Young and newly molted Rainbow Crabs are often very colorful with a purple-blue carapace and orange-red legs and tips of chelae. With age and approach to molt, carapace turns dirty yellow with occasionally slight reddish spots dorsally.

When they are young or when they have freshly molted their colors will be more vivid. As they age their colors will become lighter and more washed out.

Rainbow Crabs can grow pretty big in aquariums. Naturally, they reach 15 cm (6 inches) long, but they are likely to be nearer 7 – 12 (3 – 4 inches) when kept at home. The total weight can range between 96 – 290 g. Therefore, it will be better to give them extra space in your tank in case they grow a little larger than expected.

On average, Rainbow crabs have a lifespan of about 5 – 8 years, although there are also true long-livers among them that can live more than 10 years.