Content

• Steps
• Method 1 of 3: Part One: Identifying Females
• Method 2 of 3: Part Two: Identifying Males
• Method 3 of 3: Part Three: Understanding Difficulties
• Tips

Many people are interested in knowing what gender their goldfish is. This may be required for breeding or simply to prevent the female from giving a male nickname. Determining the sex of goldfish is easy enough, but the task can be very difficult if you don't know where to look. This article summarizes the physiological and behavioral differences between females and males.

Steps

Method 1 of 3: Part One: Identifying Females

1. 1 Look for a rounder, thicker body. Female goldfish tend to have a more rounded and thicker body than males of the same age and species.
   • They also tend to have a taller (back to abdomen) than broad body. This feature also allows you to externally determine the gender.
   • As the breeding season approaches, females begin to develop eggs, which can lead to bulging of one of the sides, making the female asymmetrical and lopsided.
2. 2 Note the protruding anus. The anal opening of the female goldfish is more rounded than that of the male, and as the breeding season approaches, it begins to protrude slightly from the body.
   • When viewed from the side, the anus may appear like a bulge on the female's abdomen.
   • In addition to the bulging anus, the anal fin of the female goldfish may be slightly denser than that of the male.

Method 2 of 3: Part Two: Identifying Males

1. 1 Pay attention to the growths. One of the clear signs by which one can say for sure that the fish is a male is the development of growths (small white tubercles) on the gill covers.
   • Usually growths appear only during the breeding season, however, in older males who have survived more than one breeding season, growths can be present all year round.
   • The growths can appear on the pectoral fins, on the head, on the scales of the body ...
   • Be aware that while the presence of growths is a good distinguishing feature of the male, their absence does not necessarily mean that the fish is a female, as not all males develop growths.
2. 2 Note the slimmer streamlined body. Males tend to have a longer slender and streamlined body than females of the same age and breed.
3. 3 Note the depressed anus. The anal opening of the male goldfish is usually narrow and elongated, which gives it a somewhat oval shape. It is also usually concave rather than convex.
4. 4 Pay attention to the bulging line of the abdomen. If possible, look at the bottom of the fish to determine if it has a scallop on its belly: a bulging line running from the pelvic fins to the anus. In females, this line is either very subtle or absent altogether.
5. 5 Pay attention to active pursuit. One of the most reliable ways to identify a male goldfish is by observing its behavior during the breeding season.
   • The male will chase the female around the aquarium, staying close behind her and slightly lower, sometimes pushing her from behind.
   • The male will also attempt to push the female against one of the tank walls or plants to force her to spawn.
   • However, in the absence of females, males will also chase each other, so it is a good idea to use a combination of physiological and behavioral traits when determining the sex of fish.

Method 3 of 3: Part Three: Understanding Difficulties

1. 1 Understand that sex differences only become noticeable in sexually mature fish. The difference between a male and a female goldfish only becomes apparent upon reaching puberty, which occurs at about one year of age.
   • However, maturation may vary depending on the species and sex of the fish. In some goldfish breeds, males become sexually mature by 9 months, while females may take up to 3 years to reach maturity.
   • There are no tests that can determine the sex of a goldfish. If you want to increase your chances of having fish of both sexes, it is best to purchase at least 6 healthy fish of the same species. There is a statistically 98% chance that at least one fish will be of the opposite sex.
2. 2 Realize that there is no 100% reliable way to sex goldfish other than by observing the spawning process. It is difficult to pinpoint the sex of a goldfish, and even experts are sometimes wrong. This is due to the large number of exceptions to the general rules:
   • Some males do not develop outgrowths, and in rare cases, outgrowths appear in females. In some females, the anus does not protrude, sometimes the anus can also bulge in males.
   • In addition, some goldfish breeds do not follow the general rules. For example, some breeds (ranchu or ryukin) are naturally endowed with a rounded, full body, which makes gender identification by body shape completely impossible.
   • As a result, it is best to determine the sex of a goldfish by looking at multiple traits in aggregate rather than just one.
3. 3 Understand that these identification methods apply only to healthy, well-fed goldfish. Affected goldfish may behave differently during the breeding season or otherwise develop distinctive sex characteristics. Therefore, it is important to ensure that the fish are in good health before sex determination (this includes good quality water and quality feed).
   • For example, a diseased male goldfish may not develop outgrowths during the breeding season, and a diseased female may not have a bulging anus.
   • Body shape can also be deceiving.A slender goldfish can be mistaken for a male (since males are usually smaller), but in fact turn out to be an underfed female. On the other hand, a bloated belly can be mistaken for a female's characteristic, but it can also be a sign of dropsy (internal bacterial infection).

Tips

• Some goldfish lovers believe that males are brighter in color and more active than females.
• Try going to the pet store and looking at the large goldfish. This can help you learn to more confidently distinguish males from females.