I think a group of Ctenolucius or Boulengerella would work well. Have mixed both with wild discus, altums, and geos. They are calmer and their behavior is very fascinating. They are all wild caught and seasonal. The good news is, now is the season.
other choices for the mid and top are Acestrorhychus species. These are colloquially callled the freshwater barracuda. Don’t let their name scare you. These are only dangerous to fish they can swallow. They would make great mates for geos. In fact, they’d be near perfect as long as you don’t mind feeding them live foods until you are able to wean them onto prepared food.
Leporinus are great mates but they may bother your three remaining angelsand they really don’t hold to a specific spot in the water column. They instead roam around munching on whatever detritus or fishes fins they can nip. If you do go with Leporinus, stay with the smaller species. Several are available now through Wetspot and Tangledupincichlids. Stay away from the banded Leporinus (Fasciatus), the Steyermarki, and the Brunneus.become a problem as they grow.
I like the chalceus idea that was mentioned and they add a nice splash of color. Keep in mind that they neeed groups of you want to minimize the torn fins they like to give eachother. Keep a small group of at least a half dozen. That will allow their conspecific aggression to be diffused a bit.
the options are literally endless. Good luck in whatever you decide.
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