When Do Molly Fry Get Their Color?

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When I first grew molly fish fry, I couldn’t wait for them to achieve colors. When I saw that they didn’t develop colors after quite some time, I started getting a little worried. Fortunately, I gained a lot of experience in this field over the years.

Molly fry usually develop bright colors during their first month. However, these will probably change as the fish grow. At four months of age, the young molly will achieve intense colors, which are also its final ones.

As we move forward, I will share some valuable tips that will allow your molly fry to achieve colors faster. They will also ensure that the fish grow healthy over the next couple of months.

Also Read: Molly Fry 101

A 30-days-old molly fry, showing subtly orangish shades.

When Do Molly Fry Get Their Color?

Most homeowners keep mollies because of their colors. Fish are pretty, and watching them explore their surroundings is surprisingly joyous. As such, you are right to obsess over the colors of your baby mollies.

Every newcomer wants to know when their baby mollies will develop their colors. After all, without their colors, fish have nothing of significance to offer. 

Typically, mollies attain adulthood within the first four months. Therefore, you can expect them to develop their colors within those first four months. 

The creatures are typically lighter at the start. But over the weeks, their bodies become darker and their colors more distinct.

That four-month duration is far broader than some aquarists would like. They would prefer to identify the exact week within which mollies develop their colors. 

But that is not possible because fish develop at different rates. In reality, your fry’s colors will probably manifest within the first month. 

At the very least, the babies will give you a vague idea of the colors you can expect within the next few weeks. But various circumstances can easily extend that duration to two, three, or four months. 

You have to consider genetic anomalies. The genetic makeup will create differences in the rate at which fish develop. Therefore, you cannot always chart a molly fry’s growth rate. 

Also Read: Molly Fry Growth Stages

A couple of days old molly fry that still hasn’t developed any colors.

Can I Make Molly Fry Gain Colors Faster?

You cannot make a molly fry gain color faster, not directly. But colors signify growth in fish; therefore, your best option is to increase the baby’s growth rate. 

You can also enhance the vibrancy of a growing fry’s colors. You can trust these methods to produce satisfying results:

1. Maintaining A Warm Environment

The temperature is one of the most impactful variables in a nursery tank. Molly fry require warm water (80 degrees F) because it makes the babies more active, boosting their metabolism and compelling the creatures to eat more food.[1]

They will grow at a faster rate which, in turn, allows the fry to develop their colors at a quicker pace.

The only significant downside is the frequent water changes you must perform to counter all the waste the babies will generate.

Also Read: How Long Do Molly Fry Take To Grow?

2. Feeding The Molly Fry Properly

The diet is the only factor more important than the temperature where fish colors are concerned. First of all, mollies will grow at a healthy rate if you provide a protein-rich diet that includes live foods and vegetables.

Secondly, while ornamental fish can develop their colors naturally, they cannot produce certain color pigments without the proper diet.

They must eat the right foods to generate certain shades of red, green, orange, and yellow. This is why aquarists add carrots to goldfish diets.[2] They deliver the orange color people associate with goldfish.[3]

You can also experiment with commercial foods that manufacturers design with the express purpose of boosting fish colors.

Two weeks old molly fry, swimming independently in its tank.

3. Dying Your Molly Fry (Not Recommended)

Some people use artificial methods to boost a molly’s colors. While they usually paint, dye, and tattoo adult fish, it is not unheard of for unscrupulous aquarists to apply artificial colors to molly fry.

However, these practices are dangerous because they introduce health problems that will probably kill your molly fry in the long run.[4]

Vets and professional aquarists tend to dismiss artificial coloring as an unethical means of enhancing a molly’s colors.

4. Keeping The Right Water Parameters

Inappropriate water parameters can stunt the growth of molly fry, delaying the time in which they should achieve their colors.

As a rule of thumb, aim for these water parameters in a molly fry tank:

  • Temperature: 75°-80°F (24°-26.7°C) 
  • pH: 7.5-8.5 GH: 12-25 dGH (200-416 ppm) 
  • KH: 10-25 dKH (178-450 ppm) 
  • Ammonia/Nitrite: 0 ppm 
  • Nitrate: <30 ppm

As I explained earlier, the temperature should be at around 80 degrees F, even though molly fry can tolerate 75 degrees F. It is more important to keep a stable temperature with a high-quality heater. 

To monitor the pH, ammonia, nitrate, and nitrite, I personally use the API Water Test Kit (link to Amazon). I found this one to be the most reliable. It also lasts for hundreds of measures, so it is pretty cost-effective.

If the pH is too low, or you found ammonia in your tank, you need to replace the water more frequently. Molly fry eat up to five times a day, and it is very common for their tank to get dirty.

As a rule of thumb, aim for weekly water changes of roughly 30 percent. You should also siphon the substrate, as it catches a lot of food residues.

5. Letting Nature Take Its Course

Some molly fry will develop their colors at a slower rate no matter what you do. You cannot alter a molly’s genetic makeup by adjusting the aquarium’s conditions.

Therefore, if your molly fry’s colors have refused to develop after two or three months, don’t fret. The baby molly will develop its colors at the time the creature’s genetic makeup has dictated.

Do Molly Fry Get Their Parents’ Colors?

Molly fry will manifest whatever colors they want. Unless you deliberately use selective breeding to produce specific colors, you cannot predict the appearance a molly fish will take when it matures.

Some mollies will mimic the colors of one parent, while others may adopt the colors of both parents. You also have baby mollies that manifest brand-new colors.

People expect sexual reproduction to produce a mix of the mother and father’s colors because each parent contributes a set of genes. But mollies can produce up to 100 fry in a single batch, and not everyone will look the same.

Also, a study from the University of Edinburgh found that the genes responsible for bright colors transition from one male generation to the next without mixing with the genes provided by the female.[5]

For that reason, don’t be surprised if male molly fry develop the striking color attributes of their male parents. But again, you cannot predict the colors a molly fry will create, not with any notable accuracy.

One week old molly fry, the internal organs start to show colors.

Do Molly Fry Change Color?

Yes and no. Some molly fish look like they changed color when, in truth, they hadn’t developed their colors yet. You should start seeing a baby molly’s colors after the first month. 

But you can’t expect those colors to represent the fry’s final appearance accurately. The creature may take three or more months to acquire its full colors. 

During that time, sections of the baby may darken or grow lighter. It may develop spots and stripes only to lose them down the line.

The severity of these changes will vary. Some molly fry will simply change shades. For instance, a lighter green can morph into a darker green or a darker red into a lighter pink.

However, you also have fry that undergo drastic color changes. Either way, these transformations are normal.

You should only panic if your molly’s colors change after that initial 3 – 4-month period when it has already seemingly matured. But even then, some fish have genetic anomalies that make significant transformations of this nature possible. 

Although, you can also blame environmental factors. That includes extreme temperatures, fluctuating pH, diseases, and more. A stress-free environment is a crucial factor in keeping molly fry alive.

You should also keep an eye on the ammonia. High concentrations can burn the skin, producing bruises that some amateur aquarists may confuse for ordinary spots, blotches, and streaks.

You should also look for signs of pregnancy. Pregnancy is stressful, and it puts mollies in a weakened state. Don’t be surprised if that stress produces a color change. It is worth noting that mollies are ready to breed within three months.

A fantastic Youtube video that shows the development of molly fry.


After four months, most baby mollies will develop colors. At this point, that will be the final appearance of the molly fish, and it is unlikely to change much.

However, that doesn’t mean that the fry won’t develop colors sooner than that. In fact, some fry will show bright shades during the first month. Yet, these colors can entirely change as time passes.


  1. https://pets.thenest.com/guppies-begin-show-color-3850.html
  2. https://edis.ifas.ufl.edu/publication/FA192
  3. https://animals.mom.com/how-to-enhance-goldfish-colors-12121312.html
  4. https://www.semanticscholar.org/paper/Some-considerations-concerning-the-artificially-E%C5%9Fanu-Gavriloaie/50cf00d10f74675235d7f94abcf4cff31bb5c553
  5. https://www.sciencedaily.com/releases/2019/03/190322105736.htm