What is your gh and kh? Angels can tolerate a considerable amount of hardness as adults, but newly hatched fry tend to be quite sensitive to excessive hardness. Hard, alkaline water can cause the fry to waste away in the time frame you are describing. REALLY hard, alkaline water can even keep wigglers from ever becoming free swimmers.
Another consideration: what sort of substrate do you have, if any? Large types allow the fry to get in between the stones and get stuck, fine gravel, sand, or no substrate at all is best. They would be especially likely to fall to the bottom at night, when the parents can't see them as well.
What sort of filtration are you using? With fry in the tank, anything other than a sponge filter is, again, liable to suck up fry.
Not being able to feed overnight isn't going to kill them, I've raised many angelfish on two feedings of bbs or microworms per day.
Another consideration: what sort of substrate do you have, if any? Large types allow the fry to get in between the stones and get stuck, fine gravel, sand, or no substrate at all is best. They would be especially likely to fall to the bottom at night, when the parents can't see them as well.
What sort of filtration are you using? With fry in the tank, anything other than a sponge filter is, again, liable to suck up fry.
Not being able to feed overnight isn't going to kill them, I've raised many angelfish on two feedings of bbs or microworms per day.