Newly hatched and just into the aquarium, fry are indeed very small and helpless. They need to be maintained with much care in order to see them safely into adulthood. They need excellent water quality and extra security, as the fry are often delicious food for the other carnivores in your aquarium. It is often a good idea to enclose the fry separately, but some fry require their parents to care for them. Usually, small sources of food suffice for fry. Live food almost always give the best results because growth rate in fish is noticed to be at least three times faster when they eat live food.
You can also use prepared mixes to feed fry. These mixtures are usually flake-based food that has been ground to a very fine powder. The obvious problem with this is that it quickly pollutes the water. Fry are often too small to be in an aquarium with vigorous filtration, and without filtration the water quality goes downhill very soon. Your fry are then at risk. Liquid mixtures tend to settle at the bottom of the aquarium, and fry are normally surface feeders, so a lot of the food does not get to them.
Infusoria refers to the various microorganisms that are present in small quantities in the water. This can be cultured and introduced in small quantities to feed fry. Just like many other types of food, Infusoria is potentially dangerous to the fry as Infusoria can foul up the water and make it toxic.
Newly hatched Brine shrimp is an excellent source of food for fry. You will be able to purchase Brine shrimp eggs from your local pet store. Take a plastic bottle; add water and one tablespoon of coarse salt to two teaspoons of brine shrimp eggs. The temperature should be around 80 Degrees F. Sufficient aeration is important. The eggs will start hatching in 24-36 hours. It is advisable to stop the aeration at this point. The Brine shrimp will settle at the bottom while the eggshells will rise to the top. Siphon out the young shrimps into a fine net, rinse thoroughly and feed the fry.
Green water or suspended algae can easily be cultured at home. Take some aged tap water and leave it in a sunny place. Remember to add some algae from your aquarium as well as a few drops of plant fertilizer to this. The algae will develop in 2-3 days. Use an eyedropper to feed this to the fry.
Egg yolk prepared at home can also be used to feed fry. After you hard-boil an egg, take a small piece of the yolk and put it in a cloth, roughly 10cm by 10 cm in dimensions. Fold this into a bag, and screw the bag so that a bit of the yolk protrudes out from the bag. Dip this bag into the aquarium to feed fry. The yolk needs to be replaced in 2-3 days, otherwise it will spoil.