Can Molly Fish Change Gender?

Can Molly Fish Change Gender?

Mollies are docile livebearer fish that are easy to care for and breed, which makes them a good choice for beginner fish keepers.

But have you ever been curious about your fish’s gender after seeing them? Or, just on occasion, wonder if your male molly fish can become females!

Molly fish are not hermaphrodites, meaning they cannot change their gender. So, a male molly will remain a male, and a female molly will remain a female for their entire lives.

In this article, we will find out whether molly fish can change gender or not, and how to determine the gender of your molly fish.

Can Molly Fish Change Gender?

Mollies can never change their gender, meaning their sex is determined at birth and will stay that way for their entire lives.

This is due to the fact that mollies’ gender can only be determined by their genetics and cannot be changed by any environmental factors.

Although you may not notice the gender right after childbirth, these guppy fish will eventually show their features, which will enable you to determine whether they are male or female.

Is Changing Gender Possible for Female Molly Fish?

It is impossible for female mollies to change gender since it is determined by their genes and cannot be altered.

However, you can see them pregnant in the all-female tank that has not come into contact with male fish for the past six months.

This is due to the fact that female molly fish species can store sperm and give birth to offspring multiple times without having any contact with male molly fish for a long time, not because they change gender.

Why Do People Think Molly Can Change Gender?

The most common reason people think mollies change gender is that they usually have the physical features of a female when they are juveniles.

However, these guppies don’t change their gender, but their physical appearance changes as they mature. 

So, you will eventually see a difference between males and females once they reach adulthood.

In addition, another reason for this misunderstanding is that molly fish can get pregnant without mating with males, but they can only retain sperm from previous encounters.

How to Identify Your Mollies’ Gender?

1. Body Shape & Size

Male mollies have skinny, short, and compact bodies with sizes between 2.5-3.5 inches.

On the other hand, females have curvier bellies and their entire bodies appear a lot rounder than males. They can grow up to five inches in length.

2. Anal & Dorsal Fins

The male’s anal fin is a thorn-shaped one that never grows wide. 

This anal fin is actually a gonopodium, which is a copulatory organ that they will use to deposit sperm inside females during mating.

However, the females have bigger and more numerous anal fins that flit about freely in the water as they swim.

Also, the dorsal fins of males are three to four times larger than those of females. In contrast, the female’s dorsal fin is shorter and blunter.

2. Color

Male mollies have a greater tendency to acquire more vibrant and bright colors than female mollies, which helps to entice female mollies into mating.

In contrast, the females’ colors are drab, timid, and demure.


What Is the Average Lifespan of Molly Fish?

The average lifespan of Molly fish is about 2 to 5 years in a well-maintained aquarium.

What Is Molly’s Natural Habitat?

The habitat of the freshwater molly fish is rivers and streams in Columbia, Central America, Mexico, and brackish water in Florida, Texas, Virginia, and Carolina.

What Do Mollies Eat?

Mollies are omnivores, which means they will eat both plant and animal matter. In the wild, they eat algae, crustaceans, and small insects.

In captivity, you can feed them a variety of foods, including flakes, pellets, freeze-dried foods, vegetables, and live foods.

Are Molly Fish Aggressive?

Molly fish are not an aggressive species and can get along with most other peaceful fish.

However, they can become territorial with their own kind or other similar-looking fish.

Can Molly Fish Survive In Cold Water?

Molly fish cannot survive in cold water since they are tropical fish.

They need warm water to thrive and will not do well if the temperature drops below 72 degrees Fahrenheit.

Do Molly Fish Need a Filter?

Molly fish need a filter to keep the water clean and free of ammonia and nitrite. Also, a filter will help to keep the water oxygenated and circulated.

Last Words

Mollies are livebearer species that do not have the natural ability for gender change, regardless of the rumor.

However, they can look the same at an early stage and only develop their sex-specific characteristics as they mature.

If you want to keep molly fish, it is important to know how to identify their gender so you can avoid unwanted pregnancies in your aquarium.

We hope this article was helpful and informative. If you have any questions or comments, please feel free to leave them below.

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