How to Tell if a Goldfish Is Male or Female

Many goldfish keepers want to know if their fish is a boy or a girl. It is not always easy. Young goldfish look alike, and fancy goldfish with round bodies are harder than most. Here are the signs to look for.

Why It Is Hard to Tell

Goldfish do not show clear differences until they are mature. For most fish this is around 8 to 12 months or older, and it can take longer for fancy types. Before that, even experts are making a best guess.

Signs of a Male Goldfish

• Breeding stars. Tiny white dots on the gill covers and the front edge of the pectoral fins. They show up most in breeding season.
• Slimmer body when you look from above.
• Vent that is flat or curves inward. The vent is the small opening near the anal fin.
• Longer, more pointed pectoral fins.
• Chasing. Males often chase females when they are ready to spawn.

Signs of a Female Goldfish

• Rounder, fuller body, especially when you look from above.
• Vent that sticks out slightly and looks rounded.
• Shorter, rounder pectoral fins.
• Few or no breeding stars.

How to Check

• Look from above, using a clear container or a tank with good light.
• Look at the vent from the side.
• Check more than one sign. One sign alone can be wrong.
• Be gentle. Keep the fish in water and do not handle it for long.

Fancy Goldfish Are Harder to Sex

Ranchu, Lionchu, and Oranda have deep, rounded bodies, so body shape is harder to judge. The size of the wen does not tell you the sex. Breeding stars and the vent are the best clues.

Is the Sex Guaranteed When You Buy?

At Garage Aquatics, we list the sex on single fish listings based on what we can see. Sex on young goldfish is not 100 percent guaranteed. You can browse single fish in our What You See Is What You Get collection.

Frequently Asked Questions

Why does my goldfish have white dots?

If they are on the gill covers and front fins, they are likely breeding stars. Ich looks different. It shows as white spots like grains of salt on the body and fins, and fish may scratch. See our ich guide.

Can two male goldfish live together?

Yes. They may chase each other a little during breeding season, but they usually do fine with enough space.

Do I need both a male and a female?

No. You only need both if you want to breed.

How old is a goldfish when you can tell?

Around 8 to 12 months or older, once breeding stars and body shape show up.

Shop Fancy Goldfish From San Diego

Browse our Ranchu, Lionchu, and Thai Oranda. See our fancy goldfish breed comparison to pick the right type.