I kept this fish a few times, for many years. I found, and this is weird but not, they liked the presence of Cryptocorynne wendtii. Both hengeli and heteromorpha seemed to want to be under them at times, and would venture out.
They were never especially shy, but I tended to keep them with similar sized small Rasbora types - Bororas and once vaterifloris, a gem of a fish you never see anymore around here.