Here is another suggestion for a tetra that has a good reputation as being hardy and peaceful. Their shape would keep them from being a target for the you Wonder killies. The Rosy tetra; Hyphessobrycon rosaceus.

The only problem is their are so many fish that look similer but act the same except one. You have the Ornate, Roberts, HY511 and the Copeland that acts like a Serpae. Of course these have even more common names but I know your a great researcher if your interested.

Just one more suggestion.