Well, my wonderful LFS had another merc in today. As Mongo has been so stubbornly planted in the same den for more than a week, I decided to bring this one home. Right now it is in a critter keeper where it will be for at least 24 hrs as there is a snow storm right now so were planted at home for a while. The way I see it, I can get a tank divider to cut the tank in half- I have one but it's too short. I can get a larger critter keeper and drill holes in it for a more permanent box in the tank with little trouble. Or I can keep him in the current keeper for a few more days then let him loose with Mongo and see how it goes. All this is assuming it survives acclimation. As mentioned, it's in the critter keeper now, I bought it a piece of rock with suitable sized holes for dens and put some small shells in so it can choose and apartment and door. I put in a hermit crab but this one doesn't seem as excited by them as Mongo is. I've placed lots of LR around the keeper on the outside of the box too add more privacy, but it's watching me as I type. So, what suggestions do you fellow TONMOers have for me?