How Big Do Mollies Get? (Ways to Increase Their Size)

How Big Do Mollies Get? (Ways to Increase Their Size)

Average-size mollies

The average size of mollies varies between 3 to 6 inches in length, depending on the species. Dwarf mollies are relatively small, while sailfin mollies grow big. An appropriate-size tank, a nutritious diet, and a favorable living environment are crucial for their optimum growth.

Average Sizes of Various Molly Species

There are several molly species, each varying in size. Some mollies grow big, while others stay relatively small.

Given below is the list of average sizes of the most popular molly species.

Molly SpeciesAverage Size
Black Molly3 to 5 inches
Black Sailfin Molly5 to 6 inches
Dalmatian Molly4.75 inches
Black Lyretail Molly5 inches
Harlequin Sailfin Molly6 inches
Golden Sailfin Molly6 inches
Platinum Lyretail Molly5 inches
Balloon Molly3 inches
Marble Lyetail Molly5 inches
Gold Dust Molly5 inches
Dwarf Molly1.5 to 2 inches
Gold Doubloon Molly5 inches

Growth Stages of Mollies

Mollies are viviparous. They give birth to live fry instead of laying eggs.

The baby mollies develop within their mother’s body after the male molly fertilizes the female molly.

Given below are the various growth stages that mollies pass through in their lifetime.

Fry Stage

Mollies give live birth to their young ones. Their fry are transparent and tiny, about half an inch in size.

Mollies are known to devour their babies. So, separating the parents is essential once the fry are born.

The fry aren’t very vibrant when they are born. They need time and a nourishing diet to bring out their colors.

The fry stage lasts for around a month before the newly born reach the next stage.

Appropriate care is essential for fry growth as they are vulnerable during this stage.

Young Stage

The fry enters the young stage after about a month from birth. At this stage, they grow up to an inch in size.

Mollies also start to show their colors and patterns in this stage.

They become more active and start to explore their environment too.

You can also identify the gender of your mollies during this stage as the reproductive organs develop.

You will notice a gravid spot in females and a gonopodium in males.

Teen Stage

Young mollies enter the teen stage at the age of two months.

They also attain their maximum growth during this stage and can reach between 4 to 6 inches in length, depending upon the species, diet, and care taken.

Mollies mature during this stage and exhibit their bright hues.

Aquarists can also breed mollies once they mature.

Eggs get developed in the females, and they can reproduce with the help of a male molly.

Mollies also get stronger once they are teens. They can defend themselves and resist diseases and parasites better.

Adult Stage

Mollies reach adulthood at the age of 4 months. They attain their maximum size and coloration during this stage.

Most mollies don’t grow beyond this stage. Even if they grow, the changes are minor and aren’t easily noticeable.

Adult mollies have a deep and round body shape. And they can be housed in a community tank with compatible tankmates.

All mollies can reproduce in adulthood. If they can’t, it might be due to a genetic abnormality that has made them infertile.

Old Age Stage

This is the last stage of mollies’ life.

They attain old age after about 3 to 4 years, depending on the lifespan of different molly varieties.

Mollies require proper care and nutrition during this stage.

They become sluggish, and their colors start to fade away.

They also become more prone to diseases and parasites due to weak immune systems.

So it’s vital to provide them with a peaceful and conducive living environment during this stage since stress can further weaken their health.

Ways to Increase the Size of Mollies

The healthier your mollies are, the faster they will grow. Proper care and nutrition in the early stages are essential for their growth.

Given below are some tips to increase the size of your mollies.

Get an Appropriate-Size Tank

Mollies in an appropriately-sized tank

Mollies don’t grow very large as some of the other freshwater fish.

However, they require an appropriately-sized aquarium for optimal growth.

There are various species of mollies, each varying in size.

Hence, you must consider their fully grown size and choose a tank that can house them comfortably.

Provide them with an aquarium of at least 10 gallons for a single molly or 20 gallons for a couple of mollies.

Another vital thing to remember is their age. Molly fry are tiny and don’t need a large tank.

They can’t survive in massive tanks as they aren’t able to reach the food. So they can starve and succumb to stress and fatigue.

Feed a Well-Balanced Diet

Adequate nutrition is the key to the optimum growth of mollies.

They need a varied diet rich in vitamins, proteins, minerals, and other nutrients to grow properly.

Being omnivores, you can feed mollies a mixed diet consisting of flakes, pellets, veggies, and live and frozen foods.

Molly fry need a protein-rich diet such as bloodworms, daphnia, egg yolk, vinegar eels, carrots, and zucchini to grow faster.

A well-balanced diet also helps to enhance their coloration and strengthen their immunity, thereby resulting in faster development.

Maintain Water Quality

Mollies need clean water to thrive. And periodic water changes are essential to maintain water quality.

You can perform a partial water change of 15% to 20% every week to ensure that the tank water is free of contaminants.

Monitoring water quality regularly with test kits can help you identify variations in water parameters.

Perform Tank Maintenance

Tank maintenance is of utmost importance for the healthy development of mollies.

Regular water changes and the removal of debris or uneaten food are essential.

Gravel or substrate needs to be cleaned and vacuumed regularly.

Installation of a filter is best to maintain water quality.

A water conditioner can also help remove chlorine or chloramine from the water.

Regularly cleaning the aquarium decorations, filters, and heater can help keep the mollies in good condition and help them grow faster.

Add Salt to The Aquarium

Mollies mainly inhabit freshwater habitats but can thrive in brackish waters. So you can add some aquarium salt to their tank.

Adding salt helps to reduce stress and can make them feel at home. Proper salt levels also help to keep the mollies healthy.

Many aquarists add salt in the early stages of a molly’s lifecycle for its healthy development.

However, you must be careful about the amount of salt you add because too much salt can harm them.

Provide a Stress-Free Environment

Providing a stress-free environment is crucial for mollies’ healthy development.

Stressful conditions can lead to stunted growth.

Conducive living conditions reduce stress, thereby stimulating growth.

Doing the following things can help create a stress-free environment for mollies:

  • Adding plenty of hiding places like plants, rocks, caves, and decorations for the mollies to rest and feel secure,
  • Maintaining good water quality and optimal water parameters,
  • Avoiding overcrowding the tank to curb their aggression,
  • Providing adequate lighting for mollies to grow faster, and
  • Housing mollies with compatible tankmates to make them feel secure and comfortable.

Factors that Hinder the Growth of Mollies

The well-being of a fish depends on the care and the environment in which it’s raised.

Mollies need conducive living conditions for optimum growth.

Given below are the numerous factors that can hinder the growth of mollies:

  • Space shortage can adversely impact mollies’ growth. It can lead to stunted growth.
  • Unfavorable water parameters outside the optimal range can hamper mollies’ growth.
  • Poor water quality and irregular water changes can also impede their growth.
  • Inadequate nutrition can lead to slow growth and poor health.
  • An overcrowded tank can cause stress and competition for food, leading to slower growth.
  • Unfavorable living conditions, such as lack of hiding places, inappropriate male-to-female ratio, aggressive tankmates, etc., can lead to stress, weakening their immunity and slowing their growth.
  • Hormonal imbalances due to stress and other environmental factors can also hinder their growth.

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