I only feed live foods to my fry and I have read about the egg yolk feeding and tried it myself, personally it was too messy for my taste, but I hear great success with its use.
Since I spawn in a more natural set-up-10g full to the top with water, very heavy planted with (95% plants) soil/sand substrate with stem, rosette, fern, moss species, as well as floating plants that are also used for nest building.
I maintain 80F water temp for spawning and for the fry-I get hatch with 24-28 hours at this temp and found that too high of temp and the eggs hatch too fast resulting in weaker fry.
Along with the common snails-pond, ramshorn, trumpet-my tank makes a lot of natural foods with infusoria being the fry first live foods they get free range and the other micro-critters that grow in natural planted tanks.
I add my first live food when the fry are about 7 days old or 3 days after they are free swimming more or less, male usually removed on day 4 and plastic veggie wrap used to cover the top of the tank to keep the air above the water warm and humid to prevent issue when the labyrinth organ develops.
First added live food on day 7 is newly hatched BBS with the yolk sac intact, carefully avoiding any egg casings of the BBS added to the fry tank, often when fry eat too many empty BBS egg shells it can cause blockage and then cause swim bladder problems and death now and then later due to deformities.
I watch the fry eat and look at their tummy, when the tummy is nice and round and pink/orange in color I know they are full. Overfeeding should be avoided.
I feed the NHBBS 2-3 times a day depending on the fry appearance, activity, number of fry...etc....
Once I start adding live foods I start making water changes, I use a homemade siphon from airline tubing and a couple of chop-stick twist tied together and my thumb works as the control valve and make 50% daily water changes.
I use gravity to replace the water with the same siphon I use to clean with.
I use a plastic bucket to collect the dirty water and once I check it for fry that may have been siphoned by accident-I dump the water and fill with clean like temp water and place it higher than the tank and use gravity flow to return the water to the tank slowly for the first two weeks of the daily water changes- then I get more aggressive and poor the water in the tank.
I make daily water changes after I start adding live foods to prevent several issues that can happen in a fry tank-water quality is so important to prevent- health, growth and development problems.
The decay of live foods or any foods can produce ammonia that even the active growth of plants can't keep up with before it can affect the delicate fry, poor water quality breeds bad parasites/pathogens, lowers immunity, stress and it can snow ball pretty fast with fry.
I don't use any filtration of any type in my fry tanks because I have been able to keep water quality and oxygen levels stable with daily water changes and active plant growth of the right types of plants.
You also need to dilute the stunting hormone that is emitted by the fry-this can only be done with water changes in a closed system. The stunting hormone naturally occur in most species of fish as a way of natural selection in a sense-survival of the biggest and strongest and we can control that to a point.
I also will start to move some of the larger fry at 2-3 weeks of age to larger grow-out tanks to give the smaller fry a better chance to develop by using a brine shrimp net.
By the time they are going into the second week I will add white worms that I culture to the mix of NHBBS-white worms are high in fat so I don't feed too much of them until they are in the 4 week area.
As they grow I will start feeding HUFA supplemented BBS-once the BBS have absorbed their yolk sac they can have very little nutrition and due to poor nutrition the fry can be seen spinning toward the bottom of the tank-some die and others that live can have health issues later in life, but most usually die. This can be avoided by supplementing the BBS with highly unsaturated fatty acid (HUFA) I use a product called "Selcon" for saltwater fish and BBS are saltwater creatures.
As the fry get bigger I add daphnia, mosquito larva, seed shrimp...etc...
I will start adding in the mix with live foods my homemade food once the fry are going into the 6-8 weeks of age and at this point most if not all fry have been moved to larger grow-out tanks with only the smallest still in the spawning tank and the ones I can't find or blend in so well you can't see until they are half inch and still in the tank with a new pair spawning
This is the only down-fall of using this type of set up in my experience-can't find all the fry
I start to separate the males I plan to sell usually at the 12-18 week mark-I use pint size canning jars and make 100% daily water changes and this is when I introduce pellet foods to wean them off live food and my homemade food-as most don't feed the way I do.
I have found that by using this size jar I get rapid growth/development of fins to catch up with their body.
By 6 months they will be placed in 1/2-to-1g size container-but usually I don't have many at this stage as most have been sold by 18 weeks, only the best are kept for spawning.
The males I plan to keep are kept in a large heavy planted tank and never separated until they are used for spawning. I have found that keeping the males together that they can be housed for up to a year without fighting in a large heavy planted tank, but once separate they can never be housed together again.
This method had worked for me for the past 3 years, before that I used the bare bottom tank method.