It’s best to wait at least 4 weeks to correctly determine the sex of guppy fry. During weeks 1 and 2, female and male guppies look exactly alike. However, once the gonopodium (anal fin) develops, you can easily tell the difference between the male and female guppy fry.
How To Sex Guppy Fry
1. Examining the Guppy’s Body Shape and Coloring
Male and female guppies have distinctive body shapes and colors. Guppies that are very slender and have long bodies are usually males. On the other hand, female guppies tend to have a rounder shape and bigger bodies compared to males.
2. Note the size of the guppy
Male guppies are usually smaller than female guppies. Females grow up to 2 ⅛ inches while males grow up to 1-⅛ inches.
3. Look for bright coloring and patterns on the guppy’s body
The more colorful guppies are more than likely males. Male guppies are covered in bright colored patterns and their tails are usually brightly colored as well.
4. Check for the gravid spot on the underside of the guppy’s tail
Female guppies have what is called a gravid spot. The gravid spot is a dark area located on the underside of a female guppy’s body usually near the anal fin and tail. The gravid spot gets darker as the female gets closer to delivering her young.
5. Examine the length and shape of the guppy’s anal fin
The anal fin is the smaller fin right before the tail fin found under the guppy fish. Male guppies have long and narrow anal fins that are slightly pointed (gonopodium). The female guppy has a triangular anal fin. The gravid spot is right above the anal fin.
6. Look at the shape of the guppy’s dorsal fin
The dorsal fin is the fin that is on the top part of the fish’s body near the head. Male guppies tend to have longer dorsal fins while female guppies have shorter dorsal fins.
Guppy Fry Female To Male Ratio
Once you can determine the gender of your guppy fry you can then separate them to prevent overpopulation. A good ratio is 1 male to 3 females. To prevent breeding, try to separate the males from the females as soon as possible.
- Gonopodium – The Free Freshwater and Saltwater Aquarium
- Can You Tell the Gender Difference in Baby Guppies? – mom.me
- Sexing Guppy Fry? | Tropical Fish Forums
- How to Identify Male and Female Guppies: 7 Steps – wikiHow
- How to tell guppy fry gender. Sorting male and female 4 weeks old guppy fry (Video)