Generally once the eggs are visible it should only be a couple days before they hatch.(if the eggs were fertilized) Depending on whether your planning on removing the fry or not reflects how post hatching goes... I remove the rock that the eggs are layed on once im sure they are properly fertilized and hatch them in a seperate tank. Once eggs hatch(either way) they are basically just tiny little wiggling nothings for about 2 days. If left with parents you probably will think they're gone. After a couple of days they grow and learn to swim and basically begin to be visible real fish(very very tiny fish). At this point they look like a swarm of ants or something. And generally if left with the parents they will herd them around and protect them from danger! Great parents! As I've said...until they're ready to spawn again...or if there is any kind of stress....or excitement (no feeder fish!)
Woah...quite the rant, my apologies
