What to do when crabs are fighting?

[OBXPair]

When your crabs start going at each other, what do y'all do? Do you separate them? Put one in ISO? Or just leave them alone and let them work it out?

The specifics of my case: I have two PPs (I think), got them about 3 weeks ago, and they're in a 10-gallon tank with 7 inches of substrate. The tank contains 4 extra shells in addition to the two the crabs are wearing, and all the shells would be a good fit. They have plenty of food, including protein and calcium, and both salt and fresh water (dechlorinated). Humidity is stable at 75-85 percent, but I've had trouble keeping the tank warm enough for their comfort, although I don't think it's dangerously low: it ranges from the low 70s to the low 80s.

They've progressed from antenna-waving and sumo-shoving to grabbing at each other with their pincher claws. So far neither has actually gotten hold of the other, but these displays seem to be escalating, so I'm afraid it's just a matter of time. They're equally matched in size. Is one of them likely to tear a limb off the other? Should I intervene before that happens? What do I do if it does happen?

[wodesorel]

Try dunking them both in the freshwater. If they still don't cool it, you may need to separate them until one changes shells, or they molt. They could kill each other or one could kill the other if they're the same size. It's rare for them to keep going at it, but pinching at each other is not okay.

[OBXPair]

Thanks, Wode. I tried squirting Jerry, the aggressor, today as a possibly-gentler alternative to dunking. He immediately retreated to another corner of the tank and didn't try to start up with Jeff again. We'll see how it goes.

I'd love to hear how some others handle such squabbles. Chime in, please, anyone.

[littleteapot123]

I think the dunking is actually to give them both a neutral smell, so you could do that any time and it might prevent another fight.

Also four isn't bad but perhaps adding some more shells of the same and larger sizes to the tank could help. I'm pretty sure the recommendation is at least 3-4 extras per crab so it's possible they're fighting over that.

Good luck!

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[kornchaser]

Funny story. Sid is one of my biggest crabs (second or third) and she loves this mix I make to the point of hogging it. She has to gobble ALL of it up before anyone else is allowed in the food dish. Flash forward to last week, Kaylee, one of my oldest and second smallest in that tank gets flicked out by Sid's leg that's about as tall as her+her shell. So Sid's noming away while Kaylee sneakily walks around the dish and behind Sid, crawls on the back of Sid's shell which makes Sid go crazy (no claws or legs went inside either of their shells that weren't their own). She's trying to reach around to Kaylee with her back legs, off-balance, turning left and right until Sid falls off the food dish and Kaylee falls off inside the food dish and then just sits there noming, not even caring that Sid is glaring at her from outside the dish. It was hilarious. My older but smaller crabs are taking back their spots when they come up from molting.

[CallaLily]

I think the dunking is actually to give them both a neutral smell,

Yep. I don't often have trouble with true aggression but I definitely recommend giving them a dunk (submerge them completely) in the freshwater pool if it's getting serious. If it continues, ISO the bully and load him/her up with good foods and extra shells. Maybe even let him molt in ISO if he's due. These things usually work, though not always.

Plenty of extra shells (check out the preferred shell guide), lots of space for each crab, offer protein and calcium daily along with other good foods, plenty of deep moist substrate - these things help reduce the risk of fighting.

[OBXPair]

Thanks, Calla, Corn, and Wode. I considered everything y'all said and tried some of it. Am holding the dunking in reserve to use if things escalate again--but I'm happy to say that the crabs seems settled and aren't squabbling so much now. They face off every so often, but there've been no recent threats with pincher claws, just normal antenna/walker claw waving. The reason they've settled down (I assume) is that I set up a 20-gallon tank and moved them from their 10-gallon one. I figured if they kept fighting I could use the 10-gallon as an ISO (and I'm keeping it in case one of them gets aggressive when the other molts...someday ). It seems to have made a big (no pun intended) difference. The 20-gallon is tall enough to allow for extra levels--an elevated moss pit, a crocheted hammock, and a climbing platform I made by securing an aquarium log to a plastic spice rack with jute twine. They also have three separate hiding places now--four if you count the area underneath the spice rack--four moss pits besides the elevated one (which keeps the humidity more stable than it was in the 10-gallon), and there's STILL plenty of room for digging-sand, spare shells, pools, and dishes. Just looking at the empty 20-gallon, I wouldn't have believed there was so much more room in it. Upper levels make all the difference!

The only thing I'm still not happy with is the temp. It remains 75F, so at least it's not fluctuating anymore, but I'm saving pennies for a more efficient, thermostat-controlled heater. Just now I've moved the tank farther from the AC vent and draped a blanket on the end nearest the vent. We'll see if that makes a difference.