The biggest difficulty in raising baby goldfish in a pond is keeping them from being eaten by grown fish. Goldfish babies, known as fry, are tiny -- about 3 mm (1/8 inch) -- and fragile. Adult fish will gobble up the fry if steps aren't taken to separate babies and adults. You can place fry in an aquarium until they grow large enough to survive in the pond, or create a floating mesh net that will protect them from predators until they're grown.
Place spawning mops in the pond. Fish will lay eggs on the mats where they will stick, making it easy to collect them before hatching.
Rinse the fish eggs off the mats with water into a bucket. The water temperature needs to be the same as the water where the eggs were hatched. The ideal water temperature for baby goldfish is 21.1 degrees C (70 degrees F).
Transfer the eggs into a 90 litre (20 gallon) aquarium filled with 15 cm (6 inches) of 21.1 degrees C (70 degrees F) water. If the water is deeper, it can crush newborn fish. If you use a filter, be sure it's turned down to low. Too strong a current created by the filter can kill the fish. Cut a slit in a filter sponge and slip it over the filter pipe. This will prevent fry from being sucked up into the filter.
Make a net out of shade netting, which you can buy at the hardware store. It's a good material for a fry net because it's soft and has no sharp edges. The net should be about 60 cm (2 feet) deep. Place small stones in the bottom of the net to help hold it down and secure the top to a floating piece of wood or foam.
Place fish eggs in the net and float it in the pond. Use the net in lieu of an aquarium to contain fry in the pond and keep larger fish from getting to them.
Feed baby goldfish liquid fry food. For the first four days, fry can only eat microscopic food contained in liquid fry food.
Offer baby fish strained egg yolks. After about four days, begin offering fry strained cooked egg yolks. Feed them egg yolks for about two weeks.
Feed growing fry brine shrimp. After about two weeks of egg yolks, fry can eat brine shrimp. For four weeks, feed them brine shrimp three times a day. After four weeks on brine shrimp, they can eat flake goldfish food. From four weeks to four months, feed fish two times daily. Be careful not to feed them more than they can eat in 20 minutes. It will pollute the water and kill the fish.