Stuff In My Tank – Porcelain Crab
One of the porcelain crabs in my tank. This one hitchhiked in and lives in the refugium. I couldn't find an accurate photo of his species so I drew one, but he had just been stood up and it carried over into the sketch.
Livestock Type – Any crustacean in the family Porcellanidae. The Wikipedia Mobile notes that these are not crabs and lists multiple species and sub-species that are grouped under a catch-all “porcelain crab” heading.
Common Name – Porcelain crab, hitchhiker crab, or anemone crab, among others.
Care Level – Depends. As there is no single “porcelain crab,” care varies; also, as many porcelain crabs are hitchhikers, care tends to be more of an accidential what the hell is that on my live rock? instead of anything planned in advance. Some hobbyists do try and cultivate homes for porcelain crabs and will provide coral and anemone with the hope that the crab will live in these structures.
Environmental Impact – Unknown. There are too many different porcelain crabs from too many regions to generalize.
Should I Put It In My Tank? – Again with the generalizations… there’s a really big risk in adding any crab to a tank, as even the so-called reef-friendly herbivores will eat your fish if the opportunity presents itself. True porcelain crabs tend to stay small and are peaceful (they aren’t crabs, remember), and most hobbyists find them to be benign and desirable. A different species of crab, though? One that you mistakenly thought was a tiny porcelain and it has since grown out of its spotty-shelled markings into something from Fright Night? Mistaken identity can become a big problem when the former porcelain crab starts to devour your livestock.
What Do I Need To Know? – Only an experienced reefer can tell if your hitchhiker is a true porcelain crab or not. If you definitely want one, use a LFS you trust to place the order from a supplier they trust, or ask them to keep an eye out for a true porcelain crab when they get shipments of coral and new live rock. As for health and quality-of-life, watch your iodine, calcium, and other trace elements that are necessary for shell growth. Since itty-bitty crabs don’t have too many visible symptoms of illness, assume that if the crab’s host animal is healthy then the crab is healthy. They also lose limbs as an escape mechanism, so don’t be surprised if a claw goes squirting off from time to time; it will grow back.
Does It Play Well With Others? – If you have a true porcelain crab, then yes. If you have a hitchhiker crab that looks like a porcelain crab but is growing into a monster, then you should determine what type of crab it is. Removing the crab to a second tank or a refugium in the meantime is the best option while you search for answers. Predatory fish, such as hawkfish and some wrasses, consider crabs of all varieties to be a tasty meal so you might lose the crab if these are in the tank.
How Will This Species Piss Me Off? – If you have a true porcelain crab, your biggest concern will be locating it when you want to watch it, or realizing that it has been eaten. False porcelain crabs cause problems of their own.
What Can I Expect To Spend? – If you really want to buy a true porcelain crab – and they are positively lovely so that’s understandable – it might cost up to $25. Or you could just buy live rock. I have at least three crabs that hitchhiked in on the rock (although one is definitely not a true porcelain).
Where Can I Buy It? – Your trusted LFS is best, or a fellow hobbyist who’s willing to give you one. As most hobbyists are fine with true porcelain crabs, be skeptical of a hobbyist who wants to unload one as quickly as possible (the exception is if he just discovered it and is concerned it will be eaten).
Any Health Hazards? – Nope!
The Digital Clownfish 