Agreed a mid sized or any tetra would gobble up those fry if given the chance. But in my tanks, (and I keep angels, eggs are higher in the tank) the angels will protect the fry from the tetras, the tetras still try (along with all the other fish) but are not able to actually get at the nest. I also get free-swimmers in my 90g with 7 BN plecos.
That said if I want to raise the fry to any size, I will move them to a nursery tank. I haven't seen the fry make it past 1.5 weeks in a community tank.