Arrow Crabs & Decorator Crabs

[TylerFerretLord]

I'm still browsing around looking for potential stock for my soon to be saltwater 29g.

Two inverts I've fallen in love with are arrow crabs and decorator crabs, but I've read conflicting evidence on whether or not they can be kept with other invertebrates and corals. In the case of the arrow crab I've heard that they will consume all coral, none, or just softies. Anyone have a good link to set this straight?

I know decorator crabs will nip at corals to attach pieces to themselves, but again, conflicting evidence as to whether this is bad or not. Some say it helps spread the corals, others say it will slowly kill them.

Can someone set me straight? I really like both of these creatures, so I may just plan my tank around them.

 

[Lynden]

I have kept two arrow crabs in the past, one years ago and another near a year ago, and both died from as of yet unknown causes. I also have a cousin that kept one, and it similarly perished. It would appear they have trouble competing with feistier tankmates for food.

Neither of mine caused any trouble. They are quite capable of preying on small fish but otherwise shouldn't be a problem. All crabs, if starved, healthy and capable, will become opportunistic; so I would suggest target feeding to keep the animal well fed.

Decorator crabs are not particularly spiffy subjects for captivity. Their ability to hide is so effective that the aquarist will be lucky to spot it (I couldn't find the one at the pet store). They are easy enough to keep, being omnivorous, and they do not predate on most reef organisms if I remember correctly, but they have been known to stick snails and hermit crabs, in addition to polyps, on their backs. The result is, the stuck creature starves to death (unless it is a polyp, in which case it will not be negatively affected). Coral colonies or polyps are almost never killed by the crab's actions, and the crab, as some of your sources will have said, may help to spread the colonies.

 

[TylerFerretLord]

So the arrow crab would be safe, but with caution and with target feeding? Got it.

The whole reason I'm getting a decorator is for my mother, as she is funding the tank and loves them. Do you think I could 'trick' the crab into wearing colorful things? The crabs at my LFS always have pieces of mesh and rubber-bands stuck on them, so they pop right out. Do you think I could place some inert, colorful objects in a pile near the crab to entice it to attach them?

Thank you very much for your help.

 

[Lynden]

I don't see why not. Just make sure they aren't too unnatural, so as to not ruin the look of the tank.

 

[TylerFerretLord]

I suppose the top-hat is out of the question, then.

I'll likely go for blue or orange, as you don't se those colors on live rock very often.

 

[Lynden]

Heh, if you can get it to wear the top-hat, fly right at 'er. The livestock do not respond negatively to a fake thing here and there. It's mainly about personal preference.

 

[TylerFerretLord]

I'm making this post for anyone who may come across this thread. I have decided to put off getting an arrow crab until I set up a larger tank with larger fish. I worry that the tank may be a bit too small for these long-legged creatures, and that the small confines may exacerbate its opportunistic nature.

I'm still going with the decorator crab, as they are not usually the type to go after a fish. I will target feed it with some algae and a piece of shrimp in order to keep it sated.

Lynden, what size tank was the one you had your arrow crabs in, and did you have any small fish?