FWIW, there is some development in his mouth, they are mostly yolk when they first hatch, and the male can sometimes spit them out early. The earliest ones I've seen look like this:
Then they start getting a little color and contour to their fins, and the yolk shrinks somewhat:
But at that point, while they can swim, they don't have a swim bladder and have to use a lot of energy to do so, so they rest on the bottom a lot. With my pair, they seem to get their swim bladder around 4 days post hatch - and there are almost always an early escapee or two before the male spits them all out, around that 4-5dph mark. They look a little less like an egg with a tail and eyes and a bit more like fish then:
Once they have their swim bladders, they can eat and will chase down any copepod sort of thing that moves. I've been able to successfully feed the fry the fines from frozen food around 1 week in, and it's a great food for them to take interest and get lots to eat.