1. Stress
   One of the most common causes of color fading in fish is stress. Aquarium fish are highly sensitive to environmental changes. Stressful situations may include:

• Sudden water changes or temperature fluctuations

• Introduction of new fish into the tank

• Living with aggressive species

• Overcrowded aquariums

• Lights being switched on and off suddenly or overly bright lighting

1. Poor Water Quality
   The quality of aquarium water directly affects the overall health of fish. High levels of ammonia, nitrite, and nitrate, or unsuitable pH levels, can cause fish to lose their color. In addition, lack of oxygen may also lead to color fading.

Suggestions:

• Perform regular weekly water changes (20–30%).

• Check your filtration system regularly.

• Use water test kits to measure pH, ammonia, nitrite, and nitrate levels.

1. Inadequate Nutrition
   To maintain their colors, fish need a high-quality and balanced diet. A lack of carotenoid-rich foods that support pigmentation can gradually lead to color fading.

Suggestions:

• Use color-enhancing specialty foods (such as those containing spirulina or astaxanthin).

• Provide a balanced diet with different types of food.

• Feed daily in controlled amounts, avoiding overfeeding.

1. Diseases and Parasites
   Certain diseases and internal/external parasites can affect a fish’s metabolism, causing its colors to fade. White spot disease, fungal infections, or internal parasites drain energy, weaken the immune system, and diminish vibrancy.

Symptoms:

• Fading colors along with loss of appetite

• Lethargic behavior

• Spots or abnormalities on the body

1. Adaptation Period and Nighttime Color Change
   Fish introduced to a new environment may temporarily lose their colors until they adapt. In addition, many species naturally become paler at night in darkness. This is completely normal, and they regain their vibrant colors with daylight.

2. Aging
   In some fish species, natural color fading occurs as they age. This process is genetically influenced and generally unavoidable, though it happens gradually and steadily.

Conclusion
Color fading in fish is often a warning sign. Sudden changes may indicate an underlying environmental stressor, a health issue, or improper care. Regular observation, maintaining proper water conditions, providing quality nutrition, and choosing compatible tank mates will help preserve both the health and the bright colors of your fish.