I used to have porcelains in my nano , they would once in awhile loose a claw from pulling too hard at the rock , or fighting over food with hermits. It doesn't seem to bother them since they have other shorter legs that they can get by with till the next molt . Mine always had a replacement claw after the next molt. Do you get to see your porcelain alot, some are known to hide but mine were in a 5.5 gallon so they were almost always there to see.