Hello; I cannot tell from the video, but they may wel be fry. A quick form of fry food has been the inside of uncooked canned peas for more than one species. I squeeze the soft inside of the pea out into the water. The pea hulls can be dropped into the tank and will grow infusoria over a few days for the fry to graze on.
If you happen to have a sponge filter that has been in operation for a time, it can be placed in the tank with the fry. I have seen fry grazing on the surface of a bubbler powered sponge filter several times. The bubbler powered sponge filter is also a safe way to aerate the water and have some filtering effect that will not suck up or damage fry.
I put an old coffee grinder to use as a dry food grinder. I have been able to grind pellets and flake food into a very fine powder this way. Some care needs to be taken to avoid overheating the food, but it does not take much food to feed a batch of fry up to larger food.
When I have time to prepare it, I make an infusoria culture by placing some lettuice leaves in some boiling water. I then set the water/ lettuice aside in a gallon container open to the air. I usually start this the first day I know of eggs being possible. It takes a couple of days or so. I usually have my breeding tank setups only about half full so there is plenty of room to pour some of the infusoria culture in each day. I also allow some bits of the, by then, dissassociated lettuice into the fry tank. These bits of lettuice will be covered with the infusoria that the fry can feed on. Usually a gallon of the stuff is enough to get fry to the size of taking other foods, but i have added more water to the jar at times. One note the infusoria culture will stink. I live alone so can do whatever I want and do not have to deal with objections.
