I am still trying to figure out what a 'Leapord C.' is... But the rest of the fish will be ok with a cory sized feather fin. I moved mine to lower my stocking, but it was with a full grown seng, a short bodied albino, a Delhezi, and a Palmas Poli, along with 3 african knifes and 2 marbled knifes(juvies) in a 90G for a month without incedent.
Since moving my featherfin into my smaller 20G living room tank, I agree with every statement about them, hiding alot during the day, swimming upside down, but not a real active scavenger. I have seen 4-5 of them at my LFS, and they were all 4"+, I got mine from Petco though.
From the above posts, I would say 3 or more clown loaches... Another one to try, as they are cheap, is a dojo loach. The one I have seems to be holding his own with an Oscar (still small @~4.5") and Asain knife(~9.%"), and even a clown knife(10+") at one point.
That fish burrows into my silica sand substrate all the time, aerating the sand and hiding from others. It also sifts the sand alot through its gills, cleaning the top 1" of sand, and is not afraid of anything! Your supposed to have more than one per tank, but mine seems fine as a loaner, as does my daughters loach...She wouldn't give it up for my tank...