To correctly sex oranda goldfish, you need a keen eye. Sexing oranda goldfish is close to impossible until the fish reach sexual maturity. Encourage spawning to make it easier to identify the gender of fish in the tank that are sexually mature.
- Inspect the oranda goldfish
Closely look at the fish in the aquarium. Oranda goldfish are approximately 3 inches in length when they are sexually mature.
- Look for white dots
Look for white dots on the gills and heads of the goldfish. These white dots are called tubercules. Do not confuse these dots with ich. Sexually mature male orandas display these tubercules during their breeding season.
- Encourage spawning
Encourage your oranda goldfish to spawn to make it easier to sex them accurately. Adjust the water temperature in the fish tank to 65 degrees Fahrenheit for a week, then raise the water temperature to 72 degrees Fahrenheit. The lowering of the temperature followed by a rise in temperature encourages spawning in oranda goldfish.
- Inspect the fish again
Look closely at your fish again after you have adjusted the water temperature. Look for breeding tubercules on any oranda goldfish that are at least 3 inches long to identify the male fish.