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new crab and dominance vs aggression

Posted: Tue Feb 02, 2021 4:48 pm
by itsabrynn
so I've had my crab fiddles for over a year and he's been doing great (multiple successful molts, very active, very friendly, etc.). but when I originally got him I didn't really know too much about them, including that they need friends. a few months ago, I actually got him a buddy and they got along great, they were sleeping next to each other by that night and I never saw any aggression or even them figuring out the alpha crab (I'm sure it happened but it must have been brief and quiet since the tank is literally next to me most of the day). unfortunately the little guy died (when I found him, he wasn't injured or anything, it looked like stress and it wasn't too long after I got him). I ended up waiting before getting another one and then fiddles went to molt.

but I finally got him a new buddy and introduced them yesterday and when they met...oh boy. I never saw any pinching or anything and neither of them got injured, but of all the dominance behavior I read about, they did pretty much all of it. they had antennae fights, pushed and shoved each other, flicked each other, climbed up and sat on each other, and fiddles was spreading his legs out to seem bigger and he even punched the new crab in the face a few times (to get him out of the coconut hut fiddles was in). I watched them for hours and it eventually got to the point where I'm pretty sure fiddles established himself as the alpha crab. and when the new crab was in the food bowl (which is pretty big), fiddles was eating off the edge (which he's always done). but when fiddles wanted to move to the middle of the bowl he just went up to the new crab, had a few second long antennae fight, poked the new crab once, and the new crab just walked away.

the one more concerning thing was one time the new crab tried to climb on fiddles and fiddles started shoving him away, and the new crab ended up going into his shell, and fiddles did grab him and turn him over. I intervened, but I didn't end up having to do more than gently nudge fiddles off of him. he basically just went "ok," walked away, and it never happened again. this was also before the food dish thing. I'm not too concerned, but still something to watch out for.

basically I'm just looking for some more opinions about what's going on with them and maybe some advice. fiddles is very important to me (I'm way too attached but he really helped me through a serious rough patch) and was doing very well on his own (he didn't seem depressed by any stretch of the imagination, I just figured he'd be even happier with a friend), and so if it seems like it's not going to work out then I would rehome the new crab. I did separate them overnight, since I couldn't watch, which I don't know if that's a good idea or not but it's what I did. also the new crab is not really shy at all, and so I was able to check and I think he's a male, and then fiddles is also a male. I dunno, thoughts?

new crab and dominance vs aggression

Posted: Tue Feb 02, 2021 5:05 pm
by jonathon1989
itsabrynn wrote:so I've had my crab fiddles for over a year and he's been doing great (multiple successful molts, very active, very friendly, etc.). but when I originally got him I didn't really know too much about them, including that they need friends. a few months ago, I actually got him a buddy and they got along great, they were sleeping next to each other by that night and I never saw any aggression or even them figuring out the alpha crab (I'm sure it happened but it must have been brief and quiet since the tank is literally next to me most of the day). unfortunately the little guy died (when I found him, he wasn't injured or anything, it looked like stress and it wasn't too long after I got him). I ended up waiting before getting another one and then fiddles went to molt.

but I finally got him a new buddy and introduced them yesterday and when they met...oh boy. I never saw any pinching or anything and neither of them got injured, but of all the dominance behavior I read about, they did pretty much all of it. they had antennae fights, pushed and shoved each other, flicked each other, climbed up and sat on each other, and fiddles was spreading his legs out to seem bigger and he even punched the new crab in the face a few times (to get him out of the coconut hut fiddles was in). I watched them for hours and it eventually got to the point where I'm pretty sure fiddles established himself as the alpha crab. and when the new crab was in the food bowl (which is pretty big), fiddles was eating off the edge (which he's always done). but when fiddles wanted to move to the middle of the bowl he just went up to the new crab, had a few second long antennae fight, poked the new crab once, and the new crab just walked away.

the one more concerning thing was one time the new crab tried to climb on fiddles and fiddles started shoving him away, and the new crab ended up going into his shell, and fiddles did grab him and turn him over. I intervened, but I didn't end up having to do more than gently nudge fiddles off of him. he basically just went "ok," walked away, and it never happened again. this was also before the food dish thing. I'm not too concerned, but still something to watch out for.

basically I'm just looking for some more opinions about what's going on with them and maybe some advice. fiddles is very important to me (I'm way too attached but he really helped me through a serious rough patch) and was doing very well on his own (he didn't seem depressed by any stretch of the imagination, I just figured he'd be even happier with a friend), and so if it seems like it's not going to work out then I would rehome the new crab. I did separate them overnight, since I couldn't watch, which I don't know if that's a good idea or not but it's what I did. also the new crab is not really shy at all, and so I was able to check and I think he's a male, and then fiddles is also a male. I dunno, thoughts?
Have you tried dipping them all in saltwater? This will give them all the same scent and from what Ive read its has worked with other crab owners on here. If that doesnt work I would isolate the agressive crab so the other ones dont get hurt.


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new crab and dominance vs aggression

Posted: Tue Feb 02, 2021 5:09 pm
by jonathon1989
This article is also very helpful and may have solutions for your agressive crab: https://crabstreetjournal.org/blog/2012 ... mit-crabs/


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Re: new crab and dominance vs aggression

Posted: Tue Feb 02, 2021 5:40 pm
by crabbycasey
I just wanted to say that I had great success with dipping each of my crabs in their freshwater after I had seen some aggression. Did this with all 5 of my crabs at the time and there was literally never an issue again!

I’m going to read that article too, haha. Good luck!


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Re: new crab and dominance vs aggression

Posted: Sat Feb 06, 2021 10:55 am
by mool
I've done the dipping method with success in the past. I've also dipped them in a neutral space--like in a high sided dishpan with dechlorinated FW. While they are sorting things out and bonding, I do a quick rearrangement of the décor so that the original crab isn't as territorial. It makes the tank more neutral to the resident crab.

Another thing that has worked (this is an old school tip) is I've taken a wooden chopstick (an essential crab keeping tool IMO) and tapped it on the back of the shell of the most aggressive crab. This supposedly mimics a crab on it's back and puts it into a defensive posture rather than an aggressive posture.

Lots of fresh clean shells in both crabs' size ranges also helps disperse aggression--hopefully they don't fight over the same shell!

Re: new crab and dominance vs aggression

Posted: Sat Feb 06, 2021 9:14 pm
by itsabrynn
yeah fiddles was definitely territorial over the coconut hut. they both wanted to be in the back in the little comfy hole fiddles had dug. I think him having been on his own for well over a year is gonna work against me here, especially since he was doing very well on his own and seemed very happy. my mom is questioning if he really will be happier with a friend at all.

I do have lots of chopsticks though so I'll keep that in mind. :)

and fiddles and the new crab are at least somewhat close in size. it's kind of hard to tell since the new crab's shell is definitely too big (even I can see that), but I'm pretty sure fiddles is bigger although not by too much. I did see new crab checking out shells, but never actually went for fiddles' shell (or vice versa). I'm gonna get some new ones as well (I have plenty for two crabs but it can't hurt), I just hope new crab switches since he's in a painted shell that very clearly isn't a good fit. :(

Re: new crab and dominance vs aggression

Posted: Mon Feb 08, 2021 10:00 pm
by mool
I've also found that crabs kept in odd numbered groups do better than crabs kept in even numbered groups (when the groups are small). I think this helps disperse aggression.

It's too late now, but it would have been better if you had bought two new crabs that were different in size than your current crab. Crabs of differing sizes don't compete as much for resources as they don't need the same things.

Adding two buddies would have dispersed the aggression from the resident. The original crab would have two new crabs to contend with thus reducing the aggression to either new crab by half.

Re: new crab and dominance vs aggression

Posted: Thu Feb 11, 2021 2:27 am
by itsabrynn
so I started dipping them and doing some supervised visits on this tray I got (so it's not familiar to fiddles either) and it's definitely gotten better. still no pinching or anything and they've never croaked/chirped at each other. they both are passionate about, well, escape, so they were mostly doing that. but there was nothing more than a couple pushes and then they'd both walk away. actually they both got to the top of the tray edge and were very close face to face and were completely fine.
and fiddles definitely is the alpha crab, it's pretty obvious. not a bad thing though because now the new crab just doesn't mess with him, so at least it's only coming from one side now. also looking at them more together, I think new crab is a good bit smaller than fiddles, even with the too big shell.

still not comfortable with them unsupervised together, but there's definitely been improvement. gonna keep working at it. :)

Re: new crab and dominance vs aggression

Posted: Thu Feb 11, 2021 8:17 am
by crabbycasey
Great news!


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Re: new crab and dominance vs aggression

Posted: Sun Feb 14, 2021 8:15 pm
by itsabrynn
ok even better news, last night I put new crab in the tank while I was there to supervise and there were a couple of pokes (it almost seemed like fiddles was investigating him instead of being aggressive) and that was it, they were in one of fiddles' favorite hiding spots together and it was totally fine. so I decided I was going to leave them overnight and they did completely fine. now they've been together for almost 24 hours and they're both doing well! I think new crab has buried himself so we'll see what happens with that, but I think they're fine to leave together now. I'm really happy and relieved. XD

Re: new crab and dominance vs aggression

Posted: Sat Mar 20, 2021 9:44 pm
by itsabrynn
ok probably final update: they've been together for like a month, and the new crab just came up from his first molt today! so the crabs are doing good and I'm really happy. :)

Re: new crab and dominance vs aggression

Posted: Sun Mar 21, 2021 10:21 am
by crabbycasey
That’s great news!


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Re: new crab and dominance vs aggression

Posted: Sun Mar 21, 2021 8:07 pm
by itsabrynn
yep! also on further inspection, new crab looks like it might actually be female. once it gets more comfortable I should hopefully be able to get a better look, but I think I do see gonopores. fiddles is definitely male, so I wonder if that affected their behavior at all (if new crab is actually female).

I was going to post a couple cute pictures of them...but apparently I don't know how to do that. oh well.

Re: new crab and dominance vs aggression

Posted: Mon Mar 22, 2021 2:00 pm
by crabbycasey
You can download Tapatalk app and post pics that way if you want...


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