After you’ve spawned some fish you need to be ready to feed the fry.
Most fry don’t need any food for the first 3 – 5 days, while they live off their yolk-sac, but then they will be ready to eat:
Food For The Tiniest Fry
Some fry such as those from Tetras, Rasboras and some other fry will need very tiny food. A product called “Egglayer” fry tube food will work fine. But if you don’t have it or can’t get it you can always use the old boiled egg trick. This involves boiling an egg, get only the yolk part and pinch off just a very small piece; put this in a small jar or vial, add some aquarium water and then shake vigorously to dissolve and disentergrate the yolk food into microscopic pieces. Then you can add just a tiny amount, maybe 2-5 drops, to the fry tank. This egg yolk food should suffice for the tiny fry for a few days until they are ready for the next step, which is:
Food For Not-So-Tiny Fry
The next step for the tiny fry would equal the foods you can use for most aquarium fish fry. Fry from fish such as Livebearers, Cichlids, Killifish, Catfish, Bettas etc, will all be able to handle fry foods such as Baby Brine Shrimp, Vinegar Eels and Microworms and crushed up flake food as a first food. Some Aquarist I know are not willing to use “Live Foods” for their fish, but there’s really no excuse for not feeding the fry live foods because it really gets them off to a much better start than just plain old flake food or even the tube foods.
Most fry will only need live foods for the first few weeks and can then be weaned off to regular fish foods.
If you are getting ready to spawn some fish you should think ahead and decide which kind of fry food you are going to use. Many fry are lost because the Aquarist isn’t ready for to feed the fry the proper foods. So check your (LPS) local pet shop for the “Egglayer Tube Food”, or get a microworm culture or Brine Shrimp Hatchery started before the arrival date of the new fry. Clean water and good food are of the major importance in raising fry, so think ahead and be prepared.