Recently one of my two crabs passed away after being attacked by my other during molting. This meant my larger crab, Cthulhu, was on his own. The schedule was not in our favor so he was by himself for about 2 months because we were in the middle of moving, then several trips. During this time I moved him from a 20 gallon to a 10 gallon for a bit easier transportation.
After all this was done I immediently started to hunt for a tank mate or two for him. I found an ad on Facebook for a hermit crab who seemed just a bit smaller than him, and went and got it. Of course about a week before I went to get the new guy, Cthulu went down to molt. Then the day after I got the new crab he too went down to molt or destress, he was on like a quarter inch of calcium sand though so it's a high possibility he's finally able to molt safely. So I've got probably 2 weeks until they can be introduced.
The problem is, this new hermit crab is TINY compared to him, maybe a fourth of his size if that. The new one, who I've named Tamatoa, is like a fourth of his size MAYBE. (since I've had him so short I haven't gotten close looks at him, just leaving him alone for the most part) and Cthulhu is large. I've attached a picture of him below, and this was pre-molt. He's a bit bigger now. (This was basically his first time out of the tank in the almost 3 years I've had him, and he was in florida humidity and like 80 degrees so it was fine, and it was only like 30 seconds)
https://imgur.com/a/lwL5O
I'm afraid Cthulu will attack Tamatoa for dominance and be a bit too rough and injure one of them. The entire time I've had him he's always been kind of aggressive, even on a high protein diet, with really no reason to attack anybody. Always plenty of shells and hides, and his casemate was maybe 3/4ths his size. I've broken up fights several times where Cthulu had pulled his cagemate out of his shell which he would in no way fit in or where he had gone over to the other food bowl with the other crab and been a jerk. Tamatoa is currently in my spare 10 gallon by himself, and if he doesn't move into a 20 gallon with Cthulu I'll get him a more suitable cage mate.
Advice? And if I just get another smaller crab for Tamatoa to be with, what should I do with Cthulhu? I of course don't want him to be alone but I don't want him being aggressive and hurting others. I just don't want either of them getting hurt. Thanks in advance!
