Eels vs Xenopus laevis

How large are the frogs and eels? I would guess that eels will eat frogs or vice versa at some point.

Espinosa? Not familiar with that name. Everything that fishbase comes up with is a fish or ray, most are marine.

I doubt that the zigzag eel will get big enough to eat the frog, and the frog will probably ignore the eel unless it is very small. My frog pays no attention to the gouramies in with her. However, I wouldn't keep these two together. The frog will do better in a bare bottom tank (to avoid sweeping in bits of substrate while eating), while the eel will need lots of places to hide and like sand to burrow in. I would worry about competition for food as well--my frog can scoop down lots of food, while my spiny eel tends to prefer searching around and is a dainty eater. They don't really come from similar water types and habitats--I would worry about the temperature difference as well.