Why Do Betta Fish Change Color?

Your betta was a brilliant red, and now his color has changed to a murky brown or pale yellow. Or your betta seems to have lost the vibrancy of their bodies and the flowing silk tapestry of their fins. You may wonder if this is normal or a cause for concern?

Betta fish change their color due to aging, stress, or dietary deficiencies. The marble and Koi bettas have a jumping gene called a transposon, creating an unstable color pattern that may change dramatically over time. Diseases such as Ich, Fin Rot, and Columnaris may also affect your betta’s color. 

Color changes and betta may be part of their normal process, and you may have nothing to worry about. However, color changes may e a symptom of psychological or physiological problems that may harm your much-loved betta. Here are the main reasons why a betta will change color and how to identify the underlying cause.

Why Bettas Change Color

Your betta color is dictated by genetics via the pigment-containing cells in the deeper layers of their skin called chromatophores. The shape of these pigment classes is branched and has finger-like projections through which the color may be distributed.

The chromatophore may spread the pigment to the extremes of the finger-like projections causing the color to be concentrated in the skin area and enhance color.

Alternatively, the chromatophore may concentrate in only one area of the cell and allow the underlying color to show through. Whether the color is intensified or muted depends on several factors mentioned below.

Purple Betta

A Natural Process of Aging

Much like humans growing gray, bettas have a fixed number of chromatophores which remain constant for most of their lifespan. However, as the betta ages, these chromatophores need to cover a larger area of skin, and the colors may pale over time or fragment.

The average age for ornamental bettas is around five years which is considerably shorter than their lifespan in the wild of about nine years. Studies show that color changes in aging fish are due to complex physiological and biochemical reactions, hormonal changes, and expression in the genes responsible for pigmentation.

Stress-Related Color Changes

Bettas can suffer from stress due to several factors, including their tank conditions, overcrowding, or mishandling. Studies show that, much like in humans, prolonged stress can create the accumulation of cortisol in bettas, which can affect the following systems:

  • Endocrine
  • Metabolism
  • Cardiovascular
  • Respiratory
  • Immune.

One of the side effects of prolonged stress is a color change in betta fish. Bettas may present stress stripes which are bands of colors that run horizontally across the body, as opposed to breeding stripes that run across the female betta vertically.

These stripes may present themselves in a variety of colors, such as:

  • Red
  • Black
  • White
  • Combination of above.

Bettas may also lose their color vibrancy and lighten or darken in shade towards grey/black.

Dietary Deficiency

Studies show that skin color change over time can be directly related to the pigment present in their diet. Cartenoids are an essential part of a Betta fish diet, and bettas cannot synthesize carotenoids and rely on their diet instead. Over time lack of carotenoids may cause a betta to fade or become dull.

Great natural sources of carotenoids for your betta fish’s diet include:

  • Spirulina
  • Brine shrimp
  • Salmon and herring (in moderation.)

Illness and Color Change

Your betta may exhibit color changes as a response to illness and infections. It would be best to look for concurrent behavioral symptoms such as lethargy, lack of appetite, and general inactivity. You may also notice your betta scratching itself against plants or substrate.

The most common cause of illness based color changes include the following:

  • Ich or White spot Disease. The freshwater parasite ichthyophthirius multifiliis affects your betta’s skin and presents as a rash of small white spots.
  • Culumnaris or cotton wool disease is caused by a bacteria called Flavobacterium columnare, which causes local skin discoloration. This disease may cause your betta to appear white or fluffy and present frayed fins and white spotting on the body.
  • Fin Rot  is caused by the Aeromonas, Pseudomonas, or Vibrio bacteria. The fins will appear milky white in color, and the edges will begin to fray or appear torn. Fin edges make also discolor to black/brown.

The Genetic Marble Gene

The marble gene in bettas refers to a ‘jumping gene’ called a transposon. Transposons are a class of genetic elements that can jump’ to different positions within a genome. The color results of this sporadic gene in bettas are evident as splotches of color or absence of color all over the body and fins.

Because the gene jumps around in position, the color patches are unstable, and your betta will show changes in color as the pigment is active or inactive. So if your betta is healthy in all other respects, color changes may be attributed to this gene.

Why Bettas Can Change Their Color 

Betta’s natural habitat in Thailand is rice paddy, shallow ponds, and even puddles. Due to their habitat, their natural color in the wild is typically a drab green/brown and gray. The wild betta evolved these colors to avoid predators by mimicking the color of the brackish water they occupy.

These dull colors were vital for survival as the wild betta only occupied a water depth of about 5.0 cm (2 inches on average, ranging from approximately 2.0 to approximately 9.4 cm). The only visible color changes occur in the wild when the bettas become agitated or engaged in courtship displays.

The fantastic color display of modern betta fish results from selective breeding in domesticated bettas. Recent studies suggest that the modern ornamental betta is the product of over 1000 years of careful selective breeding, much longer than previously thought.

The betta’s scales are not colored but instead are translucent and thin plates and fit along the body much like shingles on a roof. The process by which bettas achieve their color is more complicated than meets the eye.

Betta Color Explained

The Betta splendens scales are transparent plates that protect the fish from injury and provide streamlining for swimming. A mucus layer covers the scales to give a smoother surface and protect against parasites and bacteria.

The scales grow out from the betta’s skin and lack any defining color in themselves but are colored by the pigment cells or chromatophores found in the skin.

The color of the betta’s scales and fins are determined by the color pigments contained in the various layers of the fish’s skin. The betta has four layers of color cells that typically follow the pattern of:

  • Iridescent layer (iridocytes: tiny reflective spheres in the upper layer and lower layers of skin)
  • Black layer (Melanin)
  • Red layer (Erythrin)
  • Yellow layer Xanthin (bottom layer.)

Early betta breeders needed to ‘strip away the colors on the topmost layers through selective breeding to create a specific color. According to Bettasource, there are staggering 26,000 genetic combinations behind the kaleidoscope of colors evident in modern bettas.

Color and Genetics 

Genetic codes create the particular color of a betta fish by either increasing or decreasing the pigmentation and where the color is exhibited. The scientific name for these color traits is phenotypes and are what we perceive visually as different colors.

In turn, these color pigments are dictated by the genetic traits called genotypes which produce the reactions that create visible color in your betta.


If you are like me, you love your bettas, and each one seems to have its own personality. Color changes should always be measured in context and monitored alongside any other behavioral changes and not viewed in isolation. Best case scenario, your bettas just got a jumping gene going a bit grey like all of us will hopefully experience someday.