Take your time, research, read, think about it, reconsider, research some more, then go to the store.
green terror, oscar, jack dempsey, frontosa, convict, skat, var. puffers, mono, white tip shark, var. pleco, labs, neon tetra, cardinal tetra, discus, betta splendin, serpae tetra, mollies, pictus cat, otocinclus, blood fin tetra, cory cat, and anything else I forgot to mention.
To many to mention, all plant tanks running DIY Co2 systems.
fish don't need toys, get that crap outta the tank!
When you see signs of stress in your fish, you can then take steps to identify the source of that stress and then to resolve it before it becomes a major issue.
If you're looking for a unique way to stock your new tank, give freshwater shrimp a try.
If your fish is suffering, you may want to consider euthanasia as an option to humanely end his pain.