If the tetra is fast enough, no, but it probably could. I had some headlight tetras that were lightning-fast, so they didn't get eaten even though the bichir could easily have fit them in it's mouth.
Africans might attack the angelfish. I would say maybe a few more angles. or discuss. you want to stay on the peaceful side of fish since you have angles in the tank already. But its your tank. you can try what every you want.