2 male hermit crab problems?

[Wade]

I've had a male hermit crab for 8 years now and i have just recently gotten a new one, thinking he'd be lonely. The new one is a little smaller than the original one and is also male. Once I got him home and put him in the tank, my larger one immediately started looking aggressive. It went like this... Put him in the tank. Bigger one came up and started checking him out. 5 or 6 seconds, the bigger one jumped onto the smaller one and stayed there. 3-4 minutes later, bigger one turns new one over onto his back and i pull him off. they seemed fine for the next 5-6 hours, checking them hourly, until i checked them for the last time. The bigger one was once again on top of the upside down new one and beating him up. he was bleeding. I pulled them apart but the bigger one was grabbing hold of one of the other one's legs.

Is this normal? have I kept the other one alone for too long and now he cant be put with another one? is it that they're both male? If you could please give me your input it would be greatly appreciated. Thank you.

[Ronnie]

You're older Hermit Crab is territorial, he has lived most of his life alone and isn't used to another one just coming into his space. He is better off living alone. I'm sure he wont get along with any other crabs.

[Riley]

Obviously he is territorial. He will never be able to live with other crabs. Either buy a new set up for the new crab, or take him back to the pet store

[Bumblebee]

Territorial, honey!

[Rachel]

Hermit crabs are highly social and need species buddies to be happy but having been kept in isolation for so long your original crab probably has no clue what to make of suddenly having another around. At that age it should be also be huge with the right care.
Set up an isolation tank, let new guy heal then try monitored introductions (as in you stick around for a length of time, no hour long gaps between checks). Give the new crab AND the old crab a short dip in their salt water to remove any existing scents then place them together and watch them carefully for issues. Some fighting can occur as they sort out who is boss but full on injury shouldn't. Its also possible the old crab was trying to "shell jack" the new one if the spare shells available do not suit his needs as much as the new crab's does (or just that he thought it looked a good fit) so adding more shells may help. If this doesn't work i'd suggest joining a care group/forum or similar (facebook has some good ones like the hermit crab care and education group) so you can describe exactly what happened in more detail and also go over what injury the new crab has if it isn't minor.

Make sure the new crab has plenty of calcium, protein, fruit/veggies and maybe a blob of all natural honey available to help heal any injuries and generally get over the shock, good diet speeds recovery a lot.


Crab care has come on a lot in the past few years so it would be worth double checking your setup before reintroduction as well, certain things not being present such as a dietary component can also cause aggression. Tank size and amount of hiding places can also impact. I've added a basic setup checklist below.

It may turn out in the end your original crab can't be housed with others anymore but I would try again, if it turns out that you can't trust them together please either get the new crab a couple of species buddies or rehome him to a keeper with a good setup.

Hope this helps.

[Cheryl]

how do you know the sex of these hermit crabs ??? you can try letting them motor around in some shallow, lukewarm salt water for about ten to fifteen minutes ... it makes them smell the same and the ideal way to introduce new hermit crabs ... also make sure there are at least six spare shells of appropriate sizes in the tank at all times ...