They're known to be real non-aggressive and great community plecs even with small fish. They like cool water and lots of current. Mine is in a 100 gal with 3 Fantail Goldfish and 2 Rapahel catfish and does great. My male GT is pretty passive with other non-cichlids, if yours is the same he should do fine there. I've got 2 L191's also, they can be territorial but you'd probably just have to play it by ear. The L200 wouldn't cause a problem in either tank, I'd worry more about the other tankmates.