i had a tank when i was younger, 2 lace gouramis, 2 snakeskin gouramis, 2 sunset gouramis and two golden gouramis. with hardy plants and peppered corys. all looked and worked well together.
Since everyone is saying gourami I will add that the paradise fish is attractive.Also there are a lot of barbs that would fit, danios, or even kuhli loaches.
Hmmm nice, No on answered my fire eel question.
I've done a bit of mixing and because of the losses in my hex I'm gonna put all my larger fish in my 10 into the hex and turn the 10 to a guppy tank... ecen wit that the hex is gonna be pretty empty.
So fire eel?
Your experience with Angels is atypical. I've bred and kept Angels for over 5 years now and saw such agression only a few times. When it happens, and they do happen sometimes with long established pairs, I separate them right away or put dividers between the antagonists.
In a community tank, Angels live at peace with each other in groups of 4 or more. Even my wild Altums, Scalare, or Dumerellis, do not attack each other in the manner of your bully Angel.
Fire eels get big and can be a little tricky to care for. Gouramis are a great idea, Opaline/Gold Gouramis, Dwarf Gouramis, Pearls, and Snakeskins all have great color and as long as you keep more females than males you will not see much aggression.