One of the first things people may wonder about when they start keeping mollies is how to distinguish between male and female fish. It’s a common curiosity among aquarium enthusiasts of all experience levels. It’s critical to understand the differences, particularly if you intend to breed them or simply maintain a balanced aquarium environment.
Thankfully, once you know what to look for, telling the sexes apart isn’t too difficult. It’s easy to tell if your molly is male or female based on a few essential features. These distinctions are apparent even in early life, so it won’t take long to recognize them.
- Differences
- Size
- Sexual characteristics
- Behavioral features
- Participation in the reproduction process
- Color and activity
- Gender of fry
- Possible sex change
- Brief instructions
- Video on the topic
- Swordtails (males and females), mollies, platies, guppies and others. inhabitants of my aquarium.
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- determine the sex of a Molly When the fish will give birth, pregnancy periods
Differences
Size
Typically, females are larger. The dense abdomen of black (Mollienesia sphenops) girls grows up to 12 cm in length. The maximum length of a male representative is 8 cm. One defining characteristic is that a male’s ability to procreate increases with his size.
The Sailfin Molly (Mollienesia velifera) is one exception. Sailfin males are bigger than females. He has a large sail-shaped fin on his back that measures up to 5 cm. The medium size and unimpressive shape of the dorsal fin distinguishes females from males.
Sexual characteristics
This is the primary characteristic that sets sex apart. An anal fin is located on the underside of the fish, adjacent to the unpaired caudal fin. The female’s anal fin, in contrast to the male’s, is rounded, has restricted mobility, and can only fold and straighten. Its shape is similar to a triangle.
The male anal fin folds into a narrow tube called the gonopodium, which has a groove containing seminal fluid and a hook. The process of fertilization hooks it. The anal fin is normally pressed against the stomach, but during courtship, when the male actively and freely moves it in all directions, the fin is clearly visible.
At six to eight months old, females are already able to reproduce. The capacity to procreate first emerges in males between the ages of 8 and 12 months.
Behavioral features
Small groups with a majority of female members tend to make women feel better.
Participation in the reproduction process
A male molly covers all of the eggs in a female when he fertilizes her with sperm. While some will develop into fry right away, the remaining one will stay in it until the next spawning occurs.
A dark patch develops on the bottom, the abdomen of the pregnant female molly enlarges, and her movement becomes less. The 35–45 day gestation period is observed. They prefer to hide in thickets of algae during this time.
Aquarists advise keeping an eye on the female after she has given birth because fertilized eggs are still inside of her. She’s very likely to become pregnant again within the next month.
Color and activity
Males captivate aquarists with their large fins and vibrant coloring. Compared to women, men are more attractive.
Their body is long and flattened. They are more active than females are.
Gender of fry
Regardless of gender, the fry’s anal fin is straight when it is first born, making it impossible to tell for sure if it is male or female. From the end of the first to the start of the third month of life, the fry’s sex becomes identifiable.
Mollies are translucent and measure 6-7 mm. They lie on the aquarium floor for a while after birth instead of swimming right away. In order to protect them from being consumed by adult viviparous fish, newborns are kept apart from the other fish, including their mothers.
Possible sex change
There are tales of mollies changing their sex on forums for aquarium enthusiasts on the Internet. The female develops into a mature male that is able to conceive offspring. According to what they write, this is independent of age and is determined by the circumstances under which the fish are housed, such as a shift in water temperature. Even so, it’s not common.
Some enthusiasts for this species of fish attribute the female’s development of the gonopodium, or male genital organ, to an imbalance in hormones. They are not discussing a complete "sex change" in this instance since the degenerated female is unable to carry out male functions. The fish’s appearance is the only thing that has changed.
The majority of amateur scientists and naturalists attribute this to prolonged maturation or the process of displaying characteristics characteristic of either gender rather than a shift in sex.
Molly fry do not exhibit overt sexual differences and instead have a female appearance. A young man is misidentified as a female. It will take some time before he develops masculine traits and is prepared to procreate. For these fish, a unique term called "late males" has even been coined.
Male mollies have a pointed, rod-like anal fin called a gonopodium, whereas females have a fan-shaped anal fin. You can distinguish a female molly from a male by looking at the shape of the anal fin and body size. Particularly during pregnancy, females are frequently larger and rounder. The gender of your molly fish can be easily determined thanks to these differences.
Brief instructions
Be aware that occasionally the seller may not specify whether the fish in the aquarium are male or female when you go to a pet store to purchase a female and male molly. The traits listed below will assist you in identifying the fish’s sex on your own.
- Color: males have brighter colors.
- Behavior: males are much more active.
- Size: females are larger, and males are slimmer.
- Body shape: males are elongated, females are rounder.
- Size and shape of the dorsal fins: males have larger and more attractive fins.
- The shape of the anal fin: in the male representative it is in the form of a tube, in the female it is rounded.
Characteristic | Description |
Size | Females are usually larger and rounder than males. |
Anal Fin | Males have a pointed, rod-like anal fin (gonopodium), while females have a fan-shaped anal fin. |
Body Shape | Females have a fuller, more rounded body, especially around the belly. |
Behavior | Males may be more active and chase females during mating. |
It can be easier and more fun to care for mollies if you know how to distinguish between male and female species. This information is crucial whether you intend to breed fish or are just trying to keep your aquarium in balance.
Take note of the fish’s dimensions and form, as well as the variations in their fins. You can confidently determine the gender of your mollies with the aid of these visual cues and the behavior you witness.
As you gain experience, you’ll become more knowledgeable and competent aquarium owner by being able to quickly identify these variations.