Super Agressive Crab

[Strawblackcat]

So, I've been a hermit crabb owner for several years now, and I've owned quite a few crabs over the years, but nothing has really ever perplexed me as much as my oldest crab, Artemis. I bought her at a beach shop six years ago, and she's always been one of my favorites. That said, for some ,reason, she also is one of the most vicious hermit crabs that I've ever seen. While all of my other hermit crabs are perfectly content to live alongside other crabs, Artemis will have nothing of the sort. She'll kill ANY other crab that's in the same tank as her. It doesn't matter how big the other crab is, or how much food is in her dish (I always let her have plenty of fresh fruit/veggie scraps + dried shrimp/mealworms/bloodworms + cuttlebone), or how many other shells are in the tank -- she'll still go straight for the new crab and start to aggressively tilt the opening of the new crab's shell towards her and start trying to pry the new crab out of its shell. My only solution so far has been to isolate her from all of my other crabs in a completely separate tank, but I would really like to avoid having to do this since operating a second tank is a lot of additional work, and it takes up a lot of room.

Is there any reason why she may be doing this that I haven't considered yet? I've always been under the impression that hermit crabs were social creatures. Or is she just an introvert (like me)? She's a purple pincher, and I've only ever introduced her to other purple pinchers. Is there a possibility that her aggression is just a manifestation of her trying to assert dominance over new crabs? Replies are much appreciated!

[Hermiearth]

There are a few things that could be going on. One could be shell aggression- I know you mentioned you have lots but there useless if they are the wrong kind- have you checked out the shell guide? Also, a good tip is that when introducing a new crab that you dip them in the fresh water of the tank, as to try and dilute there scent. She could very well just be trying to show dominance, if it were me I would try to introduce her into the other tank, as to give her a new territory, maybe dip the crabs in that tank in the her old tanks fw? Idk. But I would introduce her and keep a close eye, I know any crab parents first instinct is to separate the crab at the first sign of aggression, but try and see where it goes- of a crab seems to be in direct danger separate.


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[Strawblackcat]

Yeah I've got shells of all shapes and sizes in there, so I figure that whatever preference she has is probably being met, as far as shell variety is concerned anyway. She's historically liked Spiral shells with a D-shaped opening, so I always include a few extra of those. I've always bathed new crabs before introducing them, too. Actually, it's the only time that I ever bathe my crabs, unless someone comes down with mites or something. I always do it in freshwater. Maybe I should try salt water? Or maybe I should try offering a few treat foods, like honey and stuff, during the introduction to try and tide things over? I dunno.

In any case, I got a new crab at Petco today (mine is actually pretty good compared to most -- they keep the tank moist & warm with good substrate, and the employees give you an accurate basic rundown of care when you buy them) and she's doing the same crap. Like you said, I'm just kind of watching how it goes. At this point, I figure that if the new guy makes the night, then he'll probably be in the clear. Hoping for the best.

[Hermias_mom]

If it's not a dominance thing, or a boy/girl thing, then I'd think she's hungry for some substance that she can only get from eating other crabs. Try and feed different types of protein and exoskeleton than you usually do, I would think calcium, protein, or trace minerals/nutrients is what she's after. Hermit Crab Patch makes a mineral supplement - that might help as well.

Oh, and the other possible explanation - over crowding. How many crabs do you have, what type are they, how big are they, and how big is your tank? General forum recommendations are 5 gallons per crab for small or medium crabs, and a minimum of 15 gallons for each jumbo. Jumbos also need a minimum of a 55 gallon tank - larger is better. They need the extra tank width so they can move around. There's a post on the forum about how to measure a crab's size - I think it's under Crabitat Conditions.

[wodesorel]

If you wanted to do a Help Template and/or share a few photos of her enclosure, we'd be happy to look it over and see if we can figure out what could be the cause of her being this way. I'd say a good 99% of the time it's something that's been overlooked, and once it's been fixed the aggressive crab becomes laid back again. Having a group of eyes go over everything can catch silly little things that might be missed otherwise.