How to Breed Giant Goldfish

There is no special method to breed goldfish to be giant. The size a goldfish reaches depends largely on the size of the aquarium they're kept in and proper filtration and water care. In a very large aquarium with a good filter and heater or in a pond, goldfish can grow to be 8 to 10 inches in length, or even longer and live to be 20 years old, or even older. Straight-tailed goldfish tend to be the largest. Feeding goldfish higher-protein food and keeping them in warm water will help them grow faster. There are simple steps to take to breed goldfish.

Things You'll Need

  • Two 20-gallon or larger aquariums
  • Filter
  • Heater
  • Terramycin
  • Formaldehyde
  • Copper sulphate
  • High-protein fish food
  • Live worms and brine shrimp
  • Breeder fish
  • Bushy underwater plants
  • Coconut fibers
  • Spawning mops
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Instructions

    • 1

      Buy breeder goldfish. Goldfish should be 2 to 4 years old and 4 to 6 inches long. You should buy two males for every female. It is nearly impossible to differentiate males from females, so buying fish from a breeder who has already sexed and separated fish is the only way to be sure which are which.

    • 2

      Prepare the spawning tank. Set up a separate 20-gallon or larger aquarium and equip it with bushy natural plants, coconut fibers and spawning mops; these are props necessary to get fish to breed. Place air rocks on the bottom of the tank. Spread coconut fibers over rocks and the tank floor. Place plants strategically for fish to swim into to hide. Goldfish don't necessarily need water filters, but using one will help control water quality and improve the environment. Use a heater if you live in a colder climate. Fish do better in warm water. Optimum water temperature is 72 degrees.

    • 3

      Mix 1 1/2 ounces of Terramycin, 80 drops of Formaldehyde and 6 drops of copper sulphate in four gallons of water. The water should be at the same temperature as the water the fish are living in. Place fish into the solution for 20 minutes to clean them, then move them to a separate container of fresh, clean water to rinse, then into the aquarium.

    • 4

      Feed the fish high protein fish food through the winter to build their body mass to have them ready to breed in the spring. In the early spring, switch feed to live food like worms and brine shrimp.

    • 5

      Watch for breeding tubercles --- they look like white pimples on their gill covers and the pectoral fins --- to develop on the males. Females will develop rounder bodies as it fills up with eggs or roe.

    • 6

      Watch for the spawning moment. Spawning usually happens in the early morning. The fish will become a brighter color, the fish will start grouping together and the males will start chasing the females. The male will get aggressive and push against the female until she ejects her eggs. Eggs will attach to plants, coconut fibers and spawning mops. The male will fertilize the eggs by deposit milt over them. The fish may repeat the spawning process after a couple days of rest.

    • 7

      Set up another aquarium and have it ready. Fish will lay more than 10,000 eggs in each spawning session, but fish eat their eggs, and none will survive to hatch if you leave the fish very long with the eggs. Move breeder fish to another tank as soon as spawning is complete.