HCA: Hermit Crab Association

Ok I just walked in on 2 of my crabs fighting? Eugene, who I've had for around 5 years, and my new crab, Plankton, were found like this :
I found this picture on Google to show what was happening (not my crabs). Only mine are about the same size. Their legs were all spread out and it looked like they were fighting (unless it was something else....). Right now I have plankton in a shoebox and I know he can't be there for long but I don't know what to do. Should I put my 2 new crabs in a different tank and let Eugene have the tank to himself? Or vice versa? Also I just noticed Eugene trying to get into a shell plankton was in last night. Maybe they were fighting for shells? Any help is appreciated. Thank you!


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Update:
Because this has never happened before, I panicked and made a temporary divider in the tank. I gave my old crab the big part and my 2 new crabs the little part (I know they get along) and I don't know what to do now.




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That's how they size each other up to find out who is bigger and therefore is the dominate crab. In most cases that posture prevents fights, as one comes out on top and the other backs down without it escalating. You really only need to worry if one is grabbing the other, or there is chirping, but it can get out of hand fast so they should be watched closely until one walks away.

Two of my crabs, who have lived together for almost a year, got I to a fight recently. My original crab likes to hang out with me and seemed to get mad when I brought his two tankmates out one afternoon. Usually there are no issues but for whatever reason this time, he got mad.

Long story short (kinda) when I put them back into the tank, my OC went storming across the tank and started shaking the other guy. They were making all sorts of noise (another thing that never happens) so I took Zip out and let him walk around for 5-10 minutes to cool down. When I put him back in, he was still a little grumpy and I had to seperate them one more time but he eventually calmed down. He was like that too when I added new crabs-not as aggressive but still marching around the tank like the alpha crab he is.

I would keep an eye in them but let things play out. Seperate them if it gets too rough but allow them to workout the new hierarchy on their own. If things get too nasty, and they don't calm down, try introducing them on neutral ground-somewhere outside the tank where they have room to walk away. In the wild they can walk away; their options are limited in the confines of a tank.

Just to add, though, don't try to pull them apart. That may cause more harm than good. If I gently blow on mine or spritz them with water they usually retract long enough to detach so I can move them.

@wodesorel @Kris10729
Thank you so much! This has never happened before, so I appreciate the input. I'll probably combine them tomorrow again and see how that goes. Thank you again!


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Hello,

Did you try putting everyone together again? How did it go?

@Kris10729 sorry for responding so late, yes I did. I have seen Eugene (the old big crab) pinching at plankton (new small crab) while plankton was curled up in his shell. Eugene had him facing upwards and looked like he was trying to get him out of the shell or just pinching him. I find Eugene moving around a lot but plankton just stays in his hut all day and Eugene sometimes goes in and does the same thing. They aren't getting along still; this time plankton doesn't seem to fight back. Eugene just kinda bullies him and he doesn't care (this is what it seems like). Do you think they're fighting or is it something else? Thank you for helping and replying!!


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sydrae wrote: I have seen Eugene (the old big crab) pinching at plankton (new small crab) while plankton was curled up in his shell. Eugene had him facing upwards and looked like he was trying to get him out of the shell or just pinching him.

This sounds like a shell fight to me. Check out the Preferred Shell Guide just to double check that you're offering the right types of shells. Double check sizes too.

A shell fight you definitely want to break up. A quick dunk in the freshwater and placing them at opposite ends of the crabitat usually is enough to put a stop to it. Normal dominance displays are things like antennae "fights", flicking or "punching", waving or raising claws or legs, shoving (even like what you posted in the first pic), or standing over another crab (but not pinching or trying to rip them from the shell). Usually these things do not escalate into anything serious. Most of the time one crab will back down and that'll be the end of that. It's all worth keeping an eye on though, just in case, but I don't usually intervene unless there's actual pinching or one crab is obviously going for the other's shell, like it sounds in this case.

I hope they work it all out soon. Good luck.

It could be a dominance thing - I still remember BigE flipping that smaller crab and going in for the kill. I agree though, anytime there is grabbing or pinching it needs to be broken up and the crabs may need separated.