Is it Safe to Manually Fertilize Goldfish Eggs?

Goldfish were domesticated in China more than 1,000 years ago. These hardy and attractive cold water fish are among the most popular pond and aquarium fish worldwide. Breeders selectively bred goldfish to develop various colors and body types. Goldfish spawn readily as the water temperature rises, but hobbyists can manually fertilize goldfish eggs. This is often a safety measure to ensure that the parents or other fish in the aquarium don't eat the eggs. After fertilization, the eggs require some special care to make sure fungus does not develop on them.

  1. Sexing and Problems Associated with Natural Spawning

    • Female goldfish develop eggs and take on a plump, rounded appearance at the beginning of spring. The males develop tubercles on their hard gill plates and on the first ray of their pectoral fins. In the pond environment, male goldfish begin to herd gravid females toward growths of aquatic plants or toward the spawning mop. Males also push the females against the sides of the pond in an attempt to get them to release their roe or eggs. Female goldfish typically lose scales and tear their fins during these prespawning activities. Other pond fish often eat the adhesive eggs shortly after they are laid.

    Stripping Milt

    • To strip the milt or sperm, place the male goldfish into a clean plastic container with approximately 3 inches of pond or aquarium water. Cradle the fish gently in both hands. Place your left hand over the fish's head and back and your right hand under the belly. Gently squeeze the fish's abdomen about two-thirds down the length of his body. Milt or sperm will drip into the container and will typically turn the water quite cloudy. Return the male to your pond or aquarium and stir the content of the container with your finger to make sure that the milt has mixed thoroughly with the water.

    Obtaining Eggs

    • Allow the female to release some of her eggs while still in the pond or aquarium to prevent damaging her during the stripping process. The ovaries of heavily gravid females may rapture when they are handled and removed from the water. Place the female into the container of milt and water and support her in your hands, exactly as you did with the male fish. Squeeze the fish's abdomen very gently until you notice the stream of eggs pour into the water. Return the female to her pond or aquarium. Swirl the eggs around with your finger as soon as possible, as they are sticky and tend to clump if not separated through stirring.

    Incubating the Eggs

    • Rinse the eggs several times with pond or aquarium water to flush away excessive milt and body mucus from the parents and then gently tip them into a 30-gallon aquarium that contains pond or aquarium water. Keep the water temperature at about 70 degrees F and place a sponge filter into the aquarium. The eggs will hatch in about 48-72 hours.