Well, I wasnt really thinking about an amphibian. And actually scratch the belonsox off.
So if I were to get the tank (Totally unsure) I would most likely get:
2x Bolivian Rams
1x Zig Zag Spiny Eel
1x Brown African Kniefish
no knife!!!! they will out grow the system try a 55 if you want an african knife. also they will eat small fish, that eel will out grow the 55 so make it a 75 gallon that you will need