Back when I was a young fish keeper I thought it was so easy to figure out if a guppy was a male or female. The males had big colorful tails and the females were fat and ugly. This worked for a while but as I have gotten more and more into fishkeeping I have found this is not 100% reliable.
The more and more I learn about guppies and the many different breeds and tail types the lines become more and more blurry. What also has complicated it further is that guppy breeders have been working tirelessly for decades to make female guppies more and more attractive.
We will go over various species and tail types and how to identify them specifically but let’s go over the basic ways of identifying a male or female guppy.
Body size and shape of female and male guppies can help sex them
The first thing is size, adult guppies generally have a body size difference. The males generally have a much smaller body. It will be more slender or thin of build.
While the female will be 2-3 times bigger depending on how old the fish is. Female guppies keep getting bigger as they age, unlike males who once fully grown don’t get bigger.
The shape of the body of a female guppy will also be more round. They will have a large full belly especially if the female guppy is pregnant and close to giving birth.
The body structure is going to be the most constant way of being able to sex your guppies.
Can I use the anal fin in male and female guppies to sex them?
Another reliable way to sex guppies is to look at the anal fin. This is the fin that is directly behind the pectoral fins on the underside of the fish.
If this fin is thin then it is a male guppy and if it is a triangle fin then it is a female.
This is also the best way to sex young guppies.
How to identify male and female guppy fry?
Guppy babies or fry look extremely similar tell about 4-6 weeks old when the males start to develop their color. You don’t need to wait till then to sex your guppies though. Like it is stated above you can look at the anal fins to sex them.
This method is the only reliable way to sex baby guppies. Males will have thin anal fins and the females will have large square fins.
The main reason people want to sex their baby guppies when they are young is that by the time they start showing adult sex traits they can breed. Some people just don’t want babies and guppy breeders often want to pick out the parents of the next generation of babies.
Can guppies change sex?
No guppies cannot change sex they don’t have the ability like frogs or dinosaurs in Jurassic park haha.
But because female and male guppy babies and guppy fry look very similar, people often think that all their babies are female. Then a little while later the males start getting colorful tails and tail shapes.
When trying to sex guppy babies look at the anal fin it will be the most reliable way to sex them.
Does water temperature affect guppy gender?
This is an interesting question. There are many fish that the temperature affects the gender of the babies or fry. The majority of studies on this have been with Malawi cichlids.
With Malawi cichlids, they have found at very specific temperatures you can have whole batches of babies come out male or female.
Now while there haven’t been any studies with guppies that prove you can do this with guppies. Many master guppy breeders I have talked to have sworn that the warmer the tank the more male guppies you will get and the colder the more females you will get.
In my tanks, I have also seen this to be true. I keep most of my tanks fairly warm (78-82 degrees Fahrenheit) and I would say 66-75% of my guppies come out male.
In my cold tanks (72-75 degrees Fahrenheit) I have a much more even ratio of males and females.
How to sex Fan tail and delta tail guppies?
Delta or Fan tail guppies are the easiest of all guppies to sex. They are the most common guppy type and probably the most identifiable fish maybe excluding goldfish.
Delta tail and fan tail guppy males have large tails that look like how they are described. They have a big tail that can look like the hand fans that you see in many traditional Chinese dances. The tail can be in many colors and patterns. Often these colors extend into the body of the male guppy.
As mentioned above the male will have a slender body as well and a thin anal fin.
The females will generally be less colorful. The tails will be smaller than the males. Females will usually not have any color or patterns extending into the body of the fish.
The female will have the stereotypical body type of a female guppy and over time will be much larger than the males.
How to sex swordtail guppies?
Swordtail guppies are very easy to sex because their tail shape is very different from the female guppy’s tail.
Male Swordtail guppies’ tails are just how they are described they are sword like. Unlike delta tail guppy they don’t have a large tail. Their tails have long “swords” These are long points that extend from the body of the fish.
They can have a sword on the top, bottom, or both. These are named very descriptively. You have the top tail named top swordtail guppy, the lower sword is the bottom swordtail, and if it has both it is a double swordtail.
Females will have a normal body and tail shape which makes them super easy to identify. They will have large thick bodies and normal round tails.
How to sex spade guppies?
The funny part about spade tail guppies is that the male tails have the exact shape of tail as a spade. It’s so odd that my brain always thinks, what kind of weird parasite is eating the tail into that shape? Nature does some weird things when we mess with it.
The rest of the spade tail male guppy will be similar to a delta tail or swordtail guppy.
Female guppies will get larger than males and have a large belly like all common guppy breeds. They will also usually have a tan or brown body like most female guppies.
How to sex pintail guppies?
Pintail guppies have the same body colors as captive and line bred guppies. They can be all types of patterns and colors throughout the body and tail.
The main difference between this guppy type is that instead of having round tails or big fantails it has a small rounded tail that comes to a point. This point is very prominent and makes the males easy to identify.
The females have the standard color body and tail shape. making them very different from the males. Which is nice so there is no confusion.
How to sex panda guppies?
Panda guppies are such a funky looking fish. Especially the males, they have very small bodies that are perfect for a nano tank. They generally have black bodies and large pectoral fins.
The size difference for panda guppies between males and females is a lot less dramatic. Purebred panda guppies the males and females are almost the same sizes.
Females will have a normal body shape and have little to no color to them.
How to sex Endler guppies?
The most common types of Endler guppies have a completely different look to them than most guppies. They are very small and also great for nano tanks.
They are what I feel look most like wild guppies.
The males have shiny or neon designs on the body of the male Endler guppy. Then they will also have a color on the edges of the tail. Giving the illusion of mini swordtails.
How to sex Pingu (Poecilia Reticulata varity Pingu) guppies?
Pingu guppies are one of the most colorful guppies I’ve seen. They have this cool blue, white, and yellow color combination.
The males are the only ones that get this color combination. The head is blue, the bodies are white and their tails are yellow. This makes the males super easy to identify. They have a body color like Chile’s flag which is cool.
The females are bland like most guppy females. They have tan bodies and fat abdomens.
How to sex Ginga Rubra Guppies?
Ginga guppies are a wild type of guppy that the males have a large red dot starting at the back of the abdomen with smaller red dots that continue down to the end of the tail that transitions to a yellow tail.
Some of the males have developed a peak of color that, like Endlers gives them the look of a swordtail guppy. This gene is present on the x gene so all males that carry this gene will present it.
but females will only show it if it is present on both x genes. It will show by the slightest point on the edges of the tail. The easiest way to spot this is to use a flashlight when it’s dark and look at the female’s tail. The focused light makes it pop more.
The red dots on the body remind me of the American style colorings which are pretty unique to this coloration and the gina guppies that make identifying males super easy.
The females, for the most part, have a tan body like most female guppies but Ginga guppies will have an underlying hue of yellow.
Because of all of the diversity in guppy breeds and types, it can be tough to know what sex your guppies are. Using this guide should be able to identify what type of guppies you have and how to sex. Have fun with your guppy adventures.
