Do Molly Fish Change Color? Everything You Need To Know

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Six months ago I saw that one of my mollies started losing its colors. It was a pretty young molly fish, so I thought it was merely part of aging and genetics.

However, a week later another one started showing fading colors. That was when I knew something was wrong.

In this article, I will discuss whether mollies can actually change color, what the most common color changes they experience are, and what you should do about it.

Hopefully, you’ll be able to retrieve your molly’s colors just as I did. So, without further ado, let’s get started.

Can Molly Fish Change Color?

Yes, molly fish can change color based on a variety of factors.

These factors can include water conditions, diet, stress, or the presence of other fish, allowing them to adapt their hues for camouflage, communication, or health reasons.

Common Colors Molly Fish Change To

Molly fish often exhibit a wide range of color changes based on various factors such as environment, health, and mood. There is a wide range of colors they can change to:

  • Darkening Color: Molly fish, including the Black Molly variety, can darken due to stress or poor health. This rich black color can signal less than optimal conditions.
  • Losing Color: Molly fish can lighten or turn white due to a pigment-deficient diet, environmental blending, or illness and stress.
  • Variety of Colors: Molly fish can be orange, gold, or mixed colors, usually black and white or gold and black. Orange often indicates good health, while gold and mixed colors can be naturally occurring or the result of selective breeding.
Molly fish with white patches

What Causes Molly Fish To Experience a Color Change?

There are several factors that might have caused your molly fish to change its color. Here are the main ones:

FactorsColor Change
Low Water QualityPale/Lackluster
Inappropriate TemperaturePale or Darker
Shocking EventsDarker
SicknessPaler/Spots or Patches
AgingPale/Loss of Brightness
GeneticsVaries (diverse patterns and shifts)

1. Changes Triggered by Stress

Stress can cause molly fish to sport a darker hue, a common reaction to various stressful scenarios. The following factors can trigger such stress-related color changes:

  • Tank Bullies: If molly fish share a tank with more domineering species, their stress levels could spike, leading to a defensive darkening of their color.
  • Lack of Cover: Without enough hiding places in their environment, molly fish may feel perpetually under threat, increasing stress and resulting in a darker color.
  • Overpopulation: A crowded tank can stress molly fish, possibly prompting them to darken in color, signifying their discomfort.

Also Read: Stress In Molly Fish

2. Low Water Quality

Poor water conditions can cause molly fish to display a lackluster or pale color.

Here are some water quality-related factors:

  • Off-Balance pH Levels: If the water’s pH veers away from the ideal range for molly fish, they might feel stressed and their color could lose its vibrancy.
  • Elevated Nitrate Levels: A buildup of nitrate in the tank could cause molly fish to appear less colorful, emphasizing the necessity of frequent water changes.
  • Inadequate Water Changes: Without consistent water changes, waste can pile up in the tank, degrading the water quality and leading to duller molly fish colors.

Also Read: Why Is My Molly Fish Turning White?

3. Inapropriate Temperature

If the water temperature isn’t kept within the suitable range for molly fish, they could lose their color or turn pale.

Here’s how temperature affects color:

  • Chilly Water: If the water temperature plunges below the comfortable range, molly fish may respond by becoming pale or shedding some of their vibrant colors.
  • Hot Water: Conversely, excessively warm water can also stress molly fish, causing them to potentially darken their color in response.

4. Shocking Events

Sudden alterations or shocking events can prompt a color change in molly fish, typically resulting in a darker shade.

Here are the main stressors:

  • Abrupt Environmental Shifts: Swift changes in light, temperature, or water conditions can unsettle molly fish, often causing their color to darken temporarily.
  • Predator Encounter: The introduction or existence of predators can instill considerable fear and stress in molly fish, potentially causing them to darken their color as a defense strategy.
  • Frequent Handling or Relocation: If molly fish are handled or moved excessively, they can experience considerable stress, leading to a temporary darkening of their color.

Also Read: Why Is My Molly Turning Black?

5. Sickness

When molly fish are sick, they may undergo color changes, typically turning paler or developing spots or patches.

Here are some illnesses causing color changes:

  • Parasitic Diseases: Infections, such as those instigated by ich or other parasites, can cause molly fish to develop white spots or overall paleness, indicating sickness.
  • Fungal or Bacterial Infections: Fungal or bacterial infections can make molly fish develop discolored patches, signifying poor health.
  • General Health Issues: Other health problems, like malnutrition or internal diseases, can also cause a general fading or paling of molly fish colors.

6. Aging

As molly fish grow older, their coloration can lose its brightness or become paler.

Here are some age-related factors:

  • Natural Aging Cycle: Like other organisms, molly fish can lose some of their vibrant coloring with age, often fading or becoming paler as a part of the natural aging process.
  • Lifespan: Considering that molly fish typically live around 3-5 years, these color changes can become more noticeable as they advance in years.
  • Age-Related Ailments: As molly fish age, they may also be more susceptible to diseases or health issues, which can further alter their coloration.

7. Genetics

Molly fish color is largely dictated by their genetics, leading to diverse color patterns and shifts throughout their lifespan.

Here’s how genetics contribute:

  • Genetic Variety: Different types of molly fish have been bred for their colors, implying that some color shifts can be entirely natural, based on their genetic constitution.
  • Inherited Traits: Some molly fish may inherit traits that result in unique color changes under specific conditions, demonstrating the species’ broad diversity.
  • Selective Breeding: By means of selective breeding, aquarists have managed to develop molly fish with a wide spectrum of colors and patterns, which can shift based on the various factors outlined above.

What to do If Your Molly Fish Changes Colors

Follow these steps if your molly fish changes its color unexpectedly (particularly if it has turned white or black):

1. Tackling Stress Elements

Stress might cause your molly fish to exhibit a darker color. It’s crucial to spot and manage these stressors to aid your molly fish in returning to their normal hue.

Here are some steps you can take to lessen stress:

  • Offer Ample Room: Confirm that your tank holds at least 20-30 gallons to avoid overpopulation, which could bring about stress and subsequent color shifts in molly fish.
  • Create Hiding Spots: Make sure there’s a minimum of one hideout per fish, like plants, rocks, or caves, to decrease stress levels and aid mollies in keeping their natural hue.
  • Maintain Consistent Conditions: Sudden alterations in water parameters, temperature, or light can distress molly fish. Endeavor to maintain constant conditions, within a temperature scope of 72-78°F (22-26°C) and steady lighting durations.
  • Minimize Handling: Overhandling or shifting can induce stress in molly fish, causing color alterations. Reduce handling and let them adapt when introduced to a novel environment.
  • Be Careful with Tank Companions: Refrain from pairing molly fish with notorious aggressors. Strive for a tranquil community tank to sustain their bright colors.

Here are some peaceful species that can be kept with molly fish:

  • Neon Tetra (Paracheirodon innesi)
  • Cherry Barb (Puntius titteya)
  • Zebra Danio (Danio rerio)
  • Corydoras Catfish (Corydoras spp.)
  • Harlequin Rasbora (Trigonostigma heteromorpha)
  • White Cloud Mountain Minnow (Tanichthys albonubes)
  • Kuhli Loach (Pangio kuhlii)

On the other hand, I would avoid aggressive species like:

  • Tiger Barb (Puntigrus tetrazona)
  • Redtail Shark (Epalzeorhynchos bicolor)
  • Jack Dempsey Cichlid (Rocio octofasciata)
  • African Cichlids (Various species, e.g., Melanochromis, Pseudotropheus)
  • Green Terror Cichlid (Andinoacara rivulatus)
  • Oscar Cichlid (Astronotus ocellatus)
  • Convict Cichlid (Amatitlania nigrofasciata)

Also Read: 19 Great Neon Tetra Tank Mates

2. Improving Water Conditions

Substandard water conditions can cause your molly fish to lose color or become less vibrant. Enhancing water conditions can help regain their lively shades.

Implement these measures to boost water conditions:

  • Keep pH Levels in Check: Molly fish flourish in slightly alkaline water, so target a pH level from 7.5 to 8.5 to safeguard their bright colors. You can do that with the API PROPER pH 8.2 (link to Amazon).
  • Control Nitrate Levels: Maintain nitrate levels below 20 ppm with frequent water changes, usually 25% to 50% weekly, to avert color fading.
  • Regular Water Changes: Routine water changes, at least 25% every week, assist in keeping toxins low and preserving water conditions, aiding in color maintenance.
  • Use Premium Water Conditioners: Water conditioners can eliminate harmful substances like chlorine from tap water. My recommendation: Tetra AquaSafe (link to Amazon).
  • Monitor Ammonia and Nitrite: Ideally, both should be at 0 ppm. High concentrations can induce stress and color shifts. Regularly check these levels using testing kits.

Also Read: What Is The Best pH Level For Molly Fish?

3. Fixing Temperature Differences

Molly fish favor a specific temperature range, and deviations can lead to color shifts. Bear in mind the following:

  • Optimal Temperature Range: Keep a stable temperature between 72-78°F (22-26°C) for molly fish’s comfort and color preservation.
  • Invest in a Trustworthy Heater: A top-notch, adjustable heater can assist in keeping temperature consistent, averting stress-induced color alterations. My recommendation: Orlushy Submersible Aquarium Heater (link to Amazon).
  • Check Temperature: Frequently measure the water temperature using an aquarium thermometer to identify and correct any inconsistencies promptly.
  • Avoid Sudden Shifts: Avoid rapid temperature alterations as they can distress the fish and prompt color changes.
  • Aquarium Placement: Position your aquarium away from heat or cold sources, such as windows or vents, to assist in maintaining a steady temperature.

Also Read: Molly Fish Temperature

4. Dealing with Traumatic Events

Trauma can trigger color changes in molly fish. Here’s how to manage these instances:

  • Handle Gently: When required, manipulate your molly fish delicately to lessen stress and potential injury risk.
  • Use Suitable Equipment: Use soft, adequately sized nets or containers when handling the fish.
  • Limit Handling: Attempt to handle the fish minimally, particularly when acclimating them to a new setting.
  • Check for Aggression: Routinely look for aggression signs in the tank as this can cause trauma and result in color changes.
  • Offer a Healing Area: If a molly fish gets hurt, offer a calm, secure place for recuperation, like a separate recovery tank, to help them return to their natural hue.

5. Treating Diseases

Disease often results in color changes in molly fish. Here’s how to address it:

  • Monitor Behavior: Consistently observe your molly fish for behavior alterations, as these can signal illness.
  • Feed High-quality Foods: Serve a balanced diet of premium foods to enhance your molly fish’s immunity and sustain color.
  • Regular Health Inspections: Consistently inspect your fish for illness signs, like fin rot or ick, which could result in color changes.
  • Quarantine New Arrivals: Isolate newcomers for 2-3 weeks before incorporating them into the main tank to prevent disease spread.
  • Seek Vet Assistance: If your molly fish is sick, seek advice from a vet or aquatic specialist for diagnosis and treatment to restore their health and color.

Also Read: 15 Molly Fish Diseases & Their Treatments

6. Managing Aging Effects

As molly fish grow older, they might naturally alter color. Here’s how to manage aging impacts:

  • Anticipate Changes: Realize that color alterations can be a natural aging aspect and not necessarily worrying.
  • Maintain Good Care: Persist in providing good care, including a nutritious diet and sanitary environment, as your molly fish ages.
  • Watch Closely: Closely monitor older molly fish for illness signs, as they’re more susceptible.
  • Offer Comfortable Habitat: Make sure the habitat remains comfortable for your aged molly fish, including easy access to food and resting spots.
  • Provide Appropriate Foods: Aged molly fish might need softer food, so add options like blanched veggies or specially designed senior fish food.

Also Read: How To Feed Molly Fish

7. Grasping Genetic Impacts

Genetics can impact color changes in molly fish, often noticeable as they mature or due to selective breeding:

  • Anticipate Changes with Growth: Realize that molly fish can change color as they grow, owing to genetic factors.
  • Acknowledge Selective Breeding: Understand that selective breeding often affects molly fish colors, which may shift over time.
  • Breed for Color: If desired, you can selectively breed molly fish for specific color traits, but always prioritize health over color.
  • Research Strains: Before buying, find out about the different types of molly fish. Some strains have specific color patterns due to their genetics.
  • Seek Breeder’s Advice: For precise advice on genetics and color changes, consult a trusted breeder or aquatic specialist.
The Dalmatian Molly naturally develops black dots, and there is nothing to worry about

How Can I Identify If the Color Change Is Due to Genetics or Other Factors?

To determine if a color change in your molly fish stems from genetics or other factors, you’ll need to evaluate its overall health and living conditions.

Genetic color changes typically occur as the fish matures, while environmental or health-related color changes can occur at any age.

Here are some important things to think about:

  • Monitor the Timing: Genetic shifts often align with maturity, so if your molly fish changes color as it grows, it’s probably genetic.
  • Inspect Health Signs: If your molly fish shows other signs of stress or illness such as lethargy, reduced appetite, or unusual swimming, the color change might be health-related.
  • Assess Living Conditions: Inspect water quality and tank conditions; poor water quality or stressful environments can provoke color changes in molly fish.
  • Consider the Diet: If the molly fish’s diet has recently been altered, the color change could be diet-related, not genetic.

What is the Expected Timeframe for My Molly Fish to Regain Its Original Coloration?

The timeframe for a molly fish to regain its original coloration can vary widely depending on the cause of the color change.

If the cause is environmental and adjustments are made promptly, you might see improvement within a few days to weeks.

Yet, if the color alteration results from stress, illness, or aging, the process may be more prolonged or become permanent.


For those of you in a rush, here is a quick overview of what I discussed earlier:

  • Molly fish have the ability to change color based on various factors such as water conditions, diet, stress, and genetic factors.
  • Stress can cause molly fish to darken in color, while poor water quality or unsuitable temperatures can lead to paler hues.
  • Sudden changes in the environment, traumatic events, illnesses, and aging can also prompt color shifts in molly fish.
  • To help molly fish regain their original color, it’s crucial to address stressors, improve water conditions, maintain suitable temperatures, treat diseases, and provide appropriate care for aging fish.
  • Differentiating between color changes caused by genetics or other factors requires monitoring overall health, living conditions, and considering the timing of the color shift.