lots of options, and yeah JDs tend to hide especially when by themselves, as for tankmates i would try a carpintis but they might look to similar and might fight each other, if he isnt a very aggressive JD you could try some severums in with him, you could do a FM and convict, a salvini would also be a nice fish that would be good with a JD, really just depends on what types of colors you are going for but pretty much anything in the medium aggression range that gets the same size or a bit smaller than the JD would be good