How to Identify Male and Female Goldfish?

For Goldfish keepers who are interested in breeding their Goldfish, this question is very valid. Telling male and female Goldfish apart can be a little tricky, especially for newbies. However, this article will help you identify the signs that will in turn help you identify the gender of your Goldfish.

Male goldfish are slightly smaller and skinnier than female goldfish. Female goldfish have round abdomen which is also soft. The Anal fin of male goldfish is close to the tail than female goldfish.

However, if you are uncertain as to whether you have the two genders of Goldfish in your tank or not, the identification may become trickier. But I assure you that this article will make things a lot easier for you, still. So let us go through the process of identifying the gender of your Goldfish, step by step.

The Right Time to Tell

Goldfish are very different from humans. We can easily identify the genders in most mammals and animals but identifying genders in fish can be hard. For Goldfish, there are a lot of parameters that are under consideration when telling males and females apart. Not only that, but you must also make sure that you are searching for the signs at the right time, or you may be completely wrong about your identification. So, when is the right time?

How to Identify Male and Female Goldfish

Fully Matured Goldfish

To identify the gender of your Goldfish correctly, you must wait until your Goldfish is fully matured. On average, a Goldfish reaches full maturity, in about a year. It can be hard to keep track of your Goldfish’s age if you did not see them hatch from eggs. If you bought your Goldfish from a pet store, the store owner must have told you the age of the Goldfish. This age may not be right sometimes. It is best to wait at least a year after you have bought your Goldfish as a juvenile from the pet store, to tell for sure if your Goldfish is male or female.

Spawning Season

The ideal time of the year to tell which of your Goldfish are males and which are females is the spawning season. Although some signs that help you identify the gender of your Goldfish are physical features of the Goldfish, some are also behavioral. Most of the signs, physical or behavioral, only appear best during the spawning season. This is why you must check for the gender of your Goldfish during the time they are mating.

1. Outdoors

The spring season is the ideal season for your Goldfish to spawn. This is when the temperature of the water becomes slightly warm as compared to the winters that have just ended. This mostly applies to the Goldfish that are kept outdoors in ponds.

Goldfish living outdoors

2. Indoors

For Goldfish living indoors in tanks or aquariums, you can practically make them spawn anytime you want. The spawning of Goldfish highly depends on the temperature of the water. If you keep the water temperature of your Goldfish tank warm like that in spring, your Goldfish can spawn all around the year.

Goldfish living indoors

Difference Between Male and Female Goldfish?

Once your Goldfish are old enough to reproduce and are fully matured, you can look for signs that will help you tell your male and female Goldfish apart. Let me walk you through the signs that you can observe:


If you observe one of your Goldfish chasing the other one around the tank, it is very much likely that they are trying to mate. The one chasing around is the male Goldfish and the one being chased around is the female Goldfish. However, if the chaser is hurting the Goldfish, and you observe fins being hurt and torn from the Goldfish that is being chased, it is highly likely that the other Goldfish is being bullied. The bullying is irrespective of the gender of the Goldfish.



In Goldfish bodies, a vent is an opening that the Goldfish use to let out excretory materials and waste. It is also an opening used for males to let out milt, which is Goldfish sperm, and for females to lay eggs. In female Goldfish, the vent is much rounder and protrudes outward from the body. You may want to check the anal fins of the Goldfish for the vent. In male Goldfish, the vent is flatter, and in some cases, concaved into the body of the Goldfish.

Body Shape

Female Goldfish are generally rounder in shape as compared to male Goldfish. They also have deep bodies, while the male Goldfish have more of a streamlined body shape. During the spawning season, you can clearly see that the female Goldfish is rounder from carrying the eggs in her belly. You might even be able to see bumps in her belly which are actually eggs.


Male Goldfish have narrower and longer fins as compared to female Goldfish. The fins of female Goldfish are short and thick. The male Goldfish have more beautiful fins and tails, that flow as they swim. The females have rather compact fins. However, this sign may be tricky when telling apart males and females in fancy Goldfish, as they all have flowing fins and tails.

Male Goldfish have narrower and longer fins


During the spawning season, male Goldfish develop white spots near their fins, and in some cases, all over their bodies. These are known as tubercles, and they hold the milt that will be laid on the eggs after the eggs have been laid. You can tell apart male Goldfish if they have white spots of the same size on their bodies. Some male Goldfish have tubercles all around the year, as they may have spawned a lot of times. But some male Goldfish, may not even have tubercles at all. Then it all comes down to the spawning process, and the deposit of milt, to tell if they are males.

Midline Ridge

Male Goldfish have a white line or a ridge, protruding from the pelvic fins to the vent. This can be a clear indication of the Goldfish being male.


The best way to tell if your Goldfish is male or female is when they are spawning. The male Goldfish can be seen pushing into the female Goldfish to help her spawn. The male Goldfish will push the female Goldfish into the plants or solid surfaces, to help release her eggs. This will easily tell apart the gender of your Goldfish. Some of the Goldfish may be chasing other juvenile fish, so you must also check if the Goldfish that is being chased is a female Goldfish with eggs in her belly or not.

Uncertainties in Determining the Gender of the Goldfish

As much as the signs that I have just stated are convenient for you to identify the gender of your Goldfish, there may be some uncertainties in them. These uncertainties arise due to the following reasons:

Number of Goldfish

If you are expecting to tell if your only Goldfish is a male or a female, you may want to consult an expert. The signs help you better in identification if you know for sure that both genders exist in your tank. You need to be able to compare the Goldfish with each other, to identify which is which. It is best to check with at least 5 other Goldfish to finally decide if your Goldfish is a male or a female.

Goldfish in a Tank

Healthy Goldfish

You must make sure that your Goldfish are not underfed or undernourished to tell if the body is streamlined or just slim as a result of underfeeding. Moreover, the rounded bellies in females may not be due to them carrying eggs, it is also possible that is a male Goldfish that has dropsy, which causes droopy bellies. Similarly, male Goldfish having white spots, may not be tubercles, but simple ich, especially if the spots are of different sizes, and this can occur in both male and female Goldfish.

Same age and Species

When comparing the Goldfish bodies to tell apart their genders, you must make sure that you are only comparing Goldfish that are of the same age and species. Older Goldfish may be larger and appear rounder as compared to younger Goldfish. This does not make the older Goldfish female. Similarly, fancy Goldfish are rounder and have more flowing and exaggerated fins as compared to the other species of Goldfish. Comparing a fancy Goldfish to a common one, in an attempt to identify their gender, is foolish as the fancy one may have a rounder body, and they both can still be males.

Older Goldfish


Identification of males and females in Goldfish can be very tricky. Hence, it is best to analyze all of the signs together, instead of just one. Ideally, you should do this when the Goldfish are beginning to spawn, as it will give you a clearer idea as to which one is Harry, and which is Harriet. There is a possibility that you still are wrong, after going through all the signs. This may be because your Goldfish had not fully matured yet when you identified their genders. I would still be expecting surprises in terms of their genders, up till my Goldfish have not spawned. Only then can we know for sure?  

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