3 days is about the right time for the "dwindles" to hit a tank of fry.
Although it is certainly possible to rear fry totally in captivity, they require some living food early in thier life to set thier guts to working right. By three days they are very much in need of nutrition. Artificial diets might keep them alive for that long, but that is also when we at the hatchery remove the fry from the hatchery to plankton ponds.
Next time you get a hatch, set up a second tank to raise them some food. Aquarium people call it "infusoria" and they will have many recipes for brewing it.
One recipe I know of that works pretty good.....
In a 100 gallon container that has some aeration and dechlorinated water add the following...
One quart of hard boiled iceberg lettuce and the "juice" it was boiled in.
One good armful of fresh hay or a gallon or so of dried grass clippings.
One quart of "live" water from a watergarden pool, standing water in a ditch, or if nothing else, water from the fish pond.
What you're shooting for here is rotifers, glass worms, and other very small plankters that are not easily seen with the naked eye. If you see stuff easily that is swimming around like little "bugs" you either got Daphne or Cyclops, both too big for the fry to eat, and big enough to eat the fry. These are good foods for two week old fry.
Usually the rotifers will come along in about three or four days.
Siphon some of the water from the rotifer tank to the fry tank about four or five times a day. Two or three days of this is enough then switch to artificial diet.
Timing is everything. So...
At 24 hours post hatch you will need to begin feeding the fry. You can use a mixture of hard boiled egg yolk and weight lifter's protein supplement at day one. Blend the materials then filter tham through a fine cloth or other fine material to remove the "chunks". Feed a small amount four to six times a day for the next two days. On day three switch to the rotifer soup. On day five start using the commercial "egg layer fry diet".
If so inclined, I've found that the 50 micron shrimp starter you buy from a place like AES works better than anything I;ve gotten from the pet shop.
At two weeks you can switch to ground up aquarium flakes.
All this time you must watch ammonia in the fry tank, if it elevates at all it will kill the fry. These rich soups will elevate the ammonia, so you will need to either filter tha tank or change the water regularly.
To filter the tank and not remove the fry use a couple of sponge filters. Best if they've been running in some tank water for about two weeks before you need them in your fry tank.
