Hello; I start an infusoria culture a few days before laying eggs is suspected if possible. I boil some water and pour the hot water into a container, usually a gallon jar, with some lettuice leaves in it. I set the jar aside. In a few days the jar should become cloudy as the lettuice breaks down and the infusoria starts to grow. I pour some of the mix into the fry tank when they become free swimming. I will allow a few bits of the lettuice pieces into the fry tank.
I have started brine shrimp in a gallon jar. I use hot water and the amount of salt indicated on the shrimp eggs. I have put a bubbler in the jar to keep the eggs stirred up. After a while the shrimp will hatch. I use to siphon the shrimp from the jar with air tubing and screen the eggs thru cloth in a small fold. I would then invert the cloth into the fry tank and let the shrimp into the water. I would pour the salty solution back into the brine shrimp jar. I could get several feedings from a batch this way.
I have used an old coffeee grinder to powder dry food. After cleaning the grinder I would run he food thru it a few times while adjusting it to ever finer settings. I tried to go a bit slow in the process to avoid burning the food. I imagine there are other ways to powder food.
I have fed fry the inside of uncooked canned peas. It is quick and the inside of a pea is soft enough for fry to feed on. A member posted recently that peas are not very nutritious citeing aqua culture research. I have not checked this out further, but have occasionally fed fry and adult fish peas many times over years with no notable problems. It is quick and needs no prior prep.