Wow! I think you have a wonderful tank! I certainly wish I could aquascape like that! Good job!!!!! Um, let me see . . . . . .I don't know if you have room, but a little school of neon tetras might look cool. Your profile says you don't know about the nitrogen cycle, so here's the link to read about it:https://www.fishlore.com/NitrogenCycle.htm I don't really know about plants, but I'm sure that someone else will come along who does. Good luck!
Your tank is absolutely fabulous! You've done an incredible job aquascaping!
With an 80g tank, you could look at adding a species of aggressive NW cichlid. They'll be able to stand up to the convicts. Hopefully someone will come along with an idea of NW cichlids that won't uproot your plants.
I hope this helps and we're really glad you're sharing your tank with us. It's beautiful!
I think you have done a great job aquascaping. Rather than adding fish perhaps having some kind of red plant as a feature would be the way to go. Placed just off centre a nice red plant would make a very eye catching feature.
Light is not a limiting factor for you with 400w so you could choose anything that will be tough enough to stand up to the attention of the fish. Something like an Ozelot Sword (Echinodorus Ozelot) or a Red Tiger Lotus (Nymphaea Lotus Zenkeri 'Red') would be fantastic.