blood parrots and polys

[magpie]

From my understanding a lot of fish can out compete polys for food.
You need something that grows big enough to avoid predation from your poly but won't grow too big to quickly and has a mouth too small for the poly food.
All this taken into account a surface dwelling species would also be preferable.
Cichlids I would recommend are angel fish or festivums. Other fish that could work are pink kissing guarami or snakeskin guarami.

This is why the heterospilus would be cool, because they're herbivores. They'd take a long time to grow out of your tank if you got them as 1" babies but would eventually.

And they're pretty. But they're hard to find.