4 uros may be pushing it. Here's a little something I put together way back when about introducing uros together. Definately, the rearranging of the cage is important, so I don't know if it'll work.
1) Get a fully set up and ready tank for the new arrival. Get all the temps and such right.
2) Get the new arrival acclimated to where eating is regular and gaining weight as needed.
3) After that, maybe move the tanks into the same proximity so they can see each other, and monitor them for any eating/appetite changes. After a week or two, if all looks good, try and introduce them.
4) If your going to use one of the existing tanks as their new home, you’ll need to make it a “new” home.
5) I’d remove the uro from the tank, and then take the opportunity to clean it out, including changing the substrate.
6) Rearrange the “furniture” so it really looks like a new environment. This will help eliminate any territorial issues from the one that was there originally.
7) Make sure there is at least one hideout for each uro, though three would be better (more if space allows).
8) Provide at least one food dish for each one as well as a separate basking spot for each.
9) Finally, if all goes well initially, I’d definitely watch and monitor them closely. Again, feeding and weight gain/loss. Sometimes, aggression is very passive and notice so noticeable. Watch for sores or thickening of skin in centralized places which can indicate one uro continually biting the other.
Hope it helps.
-Jim
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2.1 - Rocky, Runako, and RoxyIII (my care sheets)
