Based on my online research, here are some good tankmates for apisto's, but not all at same time obviously (barbs and angels would make quick work of neons, obviously):
All these fish can handle (or prefer) the warm, soft, acidic conditions
Tiger barbs (watch for aggression though)
Ancistrus sp
cories
Discus
Angels (6 or more- prefer wide rather than tall so they feel they can “Get away”)
Schools of not-too-spazzy tetras can provide a calming effect (dither) and may even improve rams sense of security to make spawning more likely
neons, cardinals, rummy nose especially good choices.
dwarf gouramis (small labyrinth fish in general),
pencil fish
hatchet fish
and other top dwellers like African Butterflies