Cancer antennarius

[Riptide10]

http://www.calacademy.org/RESEARCH/izg/SFBay2K/SPRP/Cancer_antennarius.htm

I have one of these in my reef tank. He's a good 2.5" in size.

Do I need to be worried?

I have a couple full grown scarlet cleaners and a full grown blood. Also hermits and some clowns and a few other fish.

I have located his burrow and if need be I can reach in (with gloves ofcourse) and forcefully pull him out of there or trap him. I don't want to bother with it unless it's really necessary.

[nemofish2217]

sure looks mean... the only way i would probably get him out is by sticking a m-80 in his hole.... ;)

[LeslieH]

They prefer to eat other crustaceans & molluscs and the bigger they get the bigger the animals they can catch. Maybe not such a good critter for your tank. Do you have a cold water reef? I'm surprised to hear he's living in a tropical tank.

[Riptide10]

Nope not a cold reef. But he looks just like that picture - with the black tipped pincers and red carapace. He's about the size of a full grown mithrax right now.

I just don't want to go to the trouble of pulling him out unless I have to. Any ideas on how long these buggers live for? And if I keep him fed (toss a few shrimp pellets in there from time to time) will he be less likely to attack my other animals?

[LeslieH]

I wonder how did a cold water crab get into your tank? If it came in on your live rock it's a warm water look-alike and your mention of black tipped pincers means it might be a xanthid. Either way, it will probably live for several years. Crustaceans will eat continuously if food is available. A few shrimp pellets may not be enough for it. If it really is an antennarius it will grow to about 7" You can just keep an eye on him & yank him if any of your other animals look injured or disappear.

[Riptide10]

I'm not sure but he definitely looks like that picture. Red carapace and black tipped pincers. I suppose that he could be a look a like species and not exactly what I thought he was. However, the situation (as you pointe out Leslie) stays the same either way.

What would you guys do? Should I leave him in there and give him a try? Or should I go after him when I change water next weekend?

Tough decision. lol