How large is you tank going to be?

 

Some comments:
keyhole are best purchased in a group of at least 5 - they are a social fish and when breeding a pair will break off (btw they pair for life); from the group to do their thing and when done rejoin the group. Mixing angels with dwarf cichild (they are not dwarf cichild) usually works since they hang high and the dwarf hang low - though having a tall aquarium (24inch or more) helps here.
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Cory/bn do not mix with most dwarf cichild if you keep m/f (if just male then it can work).
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apistogramma are a genus not a species and there is no generic answer that covers all species.
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some of the fishes mentioned will require extremely soft water for good health is your water hard or soft.
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mixing breeding dwarf cichild with keyhole (which are sort of in the middle) can be rough depending on the species of dwarf cichild as some are quite aggressive and have large territories.
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Without the tank size we cannot comment on #s.

 

Thank you for the notes, the tank is a 120 gallon 5 by 2 foot. I am undecided on the apistogramma though I’m leaning towards either fire red or cockatoo

I keep being told to get Corys. I have no real intention of breeding as my Lfs usually only stocks males

water is fairly soft from what I can remember, though I was planning on buying an ro/di filter. I’m planning roughly four months ahead in terms of my live stock choices, I like to do my research first.

 

I’ve had Denison Barbs for several years, and have never seen them try to fin nip. They’re very peaceful.