Keeping Halloween Moon Crabs as pets

Crustaceans are becoming increasingly popular as aquarium subjects. We’ve previously talked about Vampire Crabs; but today we’re looking at another species that’s a bit more challenging to keep—Halloween Moon Crabs.

Photo credit: Steve Harwood

Creating a Halloween Moon Crab Habitat

Halloween Moon Crabs are nocturnal and prefer to spend the daylight hours safely burrowed underground. In the wild, they will construct elaborate tunnels and chambers up to three feet deep. You (probably) won’t be able to provide them with this much burrowing depth in a home aquarium, but should still aim to give them at least 30 centimetres of substrate.

Moon Crabs always live in close proximity to water, and require regular access to fresh water to keep their gills moist. As much as these crabs enjoy taking a dip in the pool, they cannot swim. An artificial river bank with a gentle slope is necessary to prevent drownings.

Halloween moon crabs in the wild are found in tropical climates, and prefer the temperature to stay between 24 and 30 degrees celsius at all times. Heat lamps, aquarium heaters, and heating pads can all be used to provide warmth.

A source of salt water that’s as close as possible to sea water in terms of salinity should also be provided. They will occasionally bathe in the salty mix, and it’s thought to be helpful for the health of their shell—particularly when moulting.

Photo credit: Wikimedia Commons

Diet & Feeding

Halloween moon crabs are omnivorous, meaning they like to eat both meat and vegetables. Popular foods offered in include mealworms, crickets, leafy greens, fish, chicken, and commercial crab food. We’re a big fan of the Hikari Crab Cuisine formula.

Multiple small feedings per day are preferred over one large feeding, as much of their food is liable to spoil quickly and foul up the aquarium water.

Like many crustaceans kept in captivity, a consistent supply of calcium is important to keep their shell strong and to encourage healthy growth. Keeping a cuttlefish bone in a dry part of their tank is a good basic measure, but it may also be worth fortifying their food with a commercial calcium supplement suitable for crabs.

Breeding in captivity

…is extremely rare. Halloween Moon Crabs need access to the ocean to breed, and adequately simulating the rainforest shoreline of Panama is implausible for the average hobbyist. Unfortunately, any moon crabs you find in a local aquarium store have likely been wild caught and imported into your country.

Keeping them healthy and happy

With proper care, a Halloween moon crab can be expected to reach eight years of age.

Arguably the biggest challenge in keeping them alive this long is fulfilling their social requirements. Like other freshwater crab species, moon crabs like to hang around in small groups. Unfortunately, when living in groups, they will sometimes fight (often to the death) over territory and sexual partners. Striking a good balance between these competing forces is extremely important and requires careful observation a bit of trial and error.

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