Egg Infusion for Tiny Fry
Substitute Egg Infusion, flake food dust, wet
Feeding very tiny newly hatched fry (e.g. rainbows, tetras, anabantoids, and danios) has always been a challenge for me. Usually there is not sufficient natural infusoria in the raising tank, so fry food needs to be added. Even if there is infusoria (e.g. from live plants, biological filters, etc.), when the fry get large enough to be fed live baby brine shrimp, hydra often appear and consume the fry. That is why I like to begin raising fry in a clean bare tank. An infusoria or vinegar eel culture would be ideal to feed them on, but I find their care and maintaining a lot of work. The classical approach to feeding tiny fry artificially is with egg infusion. Infusion means simply that it is in liquid form. “Exotic Aquarium Fishes” by William T. Innes has reference to its use on page 123. I like to think I have reasonable experience breeding and raising tropical fish since I started in 1952. However, Bernie Halverson has been at it longer than I, and recently he gave me his recipe for making and using egg infusion to feed tiny fry:
Boil an egg 10-12 minutes to hard
Take a small bit of yolk and rub it in your hand with a few drops of water to make a paste
Put the paste in a small vial of water and shake vigorously
Let this set a couple of minutes so larger particles settle out
Draw the cloudy suspension with an eyedropper and feed very sparingly to fry
Light aeration will keep these tiny food particles moving and in front of the fry. Egg can be very polluting to the water, so feed a couple times a day but not much. Remember, these fry are very tiny and can’t hold much food anyway. Place snails in the tank with the free-swimming fry to consume the excess. I use snails from my daphnia culture so I know they are hydra-free. Water changes are important at this time. I use a portion of nylon stocking over the intake of the siphon so the tiny fry are not siphoned up.
Since I don’t eat eggs every day, I use a substitute also. APR and Aquamax Fry Starter are finely ground foods made for tiny fry. Instead of just putting them on the surface, I place a small amount in a glass bottle with some water and shake it up. This leaves a liquid I can feed that will stay in suspension in front of the fry. The larger particles that settle out are kept out of the fry tank, reducing pollution. I also have done this with flake food that I grind up to a very fine dust in a mortar and pestle, and it seems to work well also. Years ago I used a product called “Liquifry #1” that was an infusion for tiny fry sold in a tube. I had not seen it in several years in the local pet shops, so I looked it up on the Internet. It still is being made in England by Interpet Fish Foods. It contains a preservative that likely makes it less polluting. A more recent addition available in US pet stores is Wardleys’ “Small Fry” liquid food in a tube.
Liquid suspension foods for tiny fry have helped me raise many species of fish that might not otherwise have survived. I recommend it as a convenient and nutritious method of getting tiny fry to survive.