Crab ID

[MusicTeach]

Any idea what this is? A picture from the back of my camera.

 

[ReefNomad]

It looks like a decorator crab. There are 2 types, the "spider" type and the "arrowhead" type. This appears to be the 2nd type... but the pic isn't super clear.

 

[MusicTeach]

So sorry for the delay in getting up the actual picture - but here it is. Hopefully this helps a little.

I guess it could be an arrow crab... those are, well, bad for some fish/snails/crabs/etc., right?

For what it's worth, he moves incredibly slow.

 

[shaginwagon13]

those are, well, bad for some fish/snails/crabs/etc., right?

For what it's worth, he moves incredibly slow.

Honestly I never keep any crabs in my system. They all grow, and when they do, if they are hungry, they will eat snails or smaller fish.

They don’t need to be a fast moving or even a hard striking crab really. When your lights turn off, a lot of your fish will sleep near the bottom. That’s when crabby, if hungry, goes to work making a meal of smaller fish and inverts.

I would remove it, but that’s just me.

 

[heathlindner25]

Decorator crab

 

[ReefNomad]

Arrowhead type decorator crab

 

[MusicTeach]

There seems to be a mix of thoughts on the internet regarding their placement in the reef tank - What are your thoughts?

 

[ReefNomad]

They're not especially dangerous to anything in particular, but they will collect bits and pieces of whatever is in your tank to decorate themselves. If they pull off a little bit of green star polyp, that's not a big deal. If they grab your new $50 frag and carry it off, it's a bit more of an issue.

Another thing to consider is their strength. These crabs can bulldoze their way between rocks and corals, moving and shifting all the structure around them. If your stack isn't really locked together, these guys are about as bad as turbo snails for knocking things over.

Otherwise, they seem to be fairly docile detrivores, cleaning up after feedings and generally maintaining their territory.

 

[MusicTeach]

Well, I guess he can stay for now then but I will try to place him on the side of the aquarium with less Frags

 

[MusicTeach]

For those of you who have taken care of decorator crabs before - what do they eat? How often do you have to feed them? Found another one in the aquarium - looks like a much smaller version of what you posted (but still bigger than my other).

 

[ReefNomad]

They're completely detrivores... you shouldn't need to feed beyond what you already feed, unless you notice the crab frantically turning over rocks looking for food. Most of the time, they'll just pick a spot they feel safe and proceed to give the area within reach a good clean-up.