Is there such a thing as a powdered food that you can spread all over the tank, but also won't go bad if it falls into a crack or below the substrate?
For example, the Glas Garten Shrimp Baby food, which is high in protein, does go bad and pollute the water. (I think I killed off a bunch of shrimp due to uneaten pieces of it sitting around). I also did a test where I just put it along with some tank water in a test tube and it went stinky and moldy within a few days.
Bacter AE seems to be ok, since the clumps are bacteria that go live.
Probably dried mulberry pellets should also be ok, since it should be safe to have plant matter decay?
How about bee pollen? Or maybe the algae powders like Spirulina or chlorella?
I have a friend that hatches BBS so it must be fairly easy (I have not tried it), so maybe give it a go for the start to give the baby fish the best start then move on to other food? I guess there is no difference than frozen brine shrimp though!
I have never had baby fish, but feed all my fish baby fish food anyway as they are small fish. I think it is the same as normal fish food just powder! I dip a pln into the tank to wet it, then into the powder food quickly, then swirl the pin in the tank to feed the fish!