I would first judge stocking by the testing nitrate just before and after a regularly scheduled water change.
If nitrate concentration was above 5 ppm, I'd get rid of the tinfoil.
If before the next scheduled water change, nitrate levels were still above 5 ppm, I lose the tiger barbs.
If before the next water change, nitrate was still high, instead of thinning more fish, I'd double up on water change schedule frequency and volume.
But....
the thinning choices I made, are also based on eventual size of the tinfoil, and the tendency of tiger barbs to whittle away at the fin trailers of the Acarichthys
and are also based on geography, and what fish would actually be found together in nature,
it appears you may have a South American theme/biotope with the cichlids and SDs. so that's the geographic reason
but...
maybe if an Asian theme is desired, in that case, I'd lose all the the new world fish and keep the barbs