Why Is My Fish Losing Its Color?

You chose the brightest, most vibrantly colored fishes at the pet store – reds, golds, and blues. They brought your aquarium to life, but their shimmering colors are fading. They’re looking dull, and maybe even behaving listlessly.

What is wrong with your fish? Why is it losing its color? Below, we’ll explore the most common reasons why aquarium fishes’ colors fade. We’ll also provide solutions to help your finny friends look and feel their best.

Why Do Fish Lose Their Color?

There are many reasons why your fish may display faded colors. Some are related to temporary conditions, while others may require immediate action to prevent adverse outcomes.

Water Quality

Poor water quality is one of the most common reasons for changes in fish health. Elevated ammonia, phosphate, nitrite, and nitrate levels or a pH that is too low or too high can be toxic to fish. They may show the resulting stress as a loss of color.

If your fishes lose color, test your water immediately. At-home test kits are readily available, and many pet stores offer free water testing. Such testing should be a regular part of your aquarium maintenance routine.

What should you do if your test results show a need for change? You may be able to adjust pH levels rapidly by using chemicals, but be careful not to change the pH by more than 0.2 per day; otherwise, it can shock the fish, resulting in death.

Make sure you are using an adequate filter system, one rated for the size of your tank. If you are keeping a large number of fish, you might even consider using a filter that is recommended for the next tank size up.

Change your filter media to make sure it is doing its job. You should also regularly change a portion of the aquarium water. Conduct a 20 percent water change at least every two weeks. You can start with a 30 to 50 percent water change to give things a jump-start. Don’t forget to let the water reach room temperature before adding it to the tank, and provide an adequate dose of dechlorination solution.

Finally, make sure that the amount of food is not impacting water quality. Fish should be able to consume all food placed in the tank within a few minutes.


Fish derive oxygen from the water just as we do from the air. But stagnant or non-moving water can contain too little dissolved oxygen to keep fish healthy, especially if water quality is poor.

The solution is to use adequate filtration or install an air pump. Either of these will keep the water moving.


Tropical fish need a constant temperature of 75 to 80 degrees F in order to thrive. Goldfish and other “cold-water” fish need temperatures slightly lower than 70 degrees.

Do research to find out the exact needs of your fish. Then, install an aquarium thermometer to monitor the temperature. Most tropical home aquariums also require an aquarium heater to keep water temperatures within the proper range.


Moving from one environment to another is stressful for the fish. Think about it – they’ve been shipped to the pet store, kept in overcrowded display tanks, chased with a net, and faced with different water conditions. This stress can cause colors to fade.

To combat this, plan your fish purchases to minimize the time between purchasing and introducing the fish to its new home. Always float the transport bag in the new aquarium for at least 30 minutes so that the temperatures can slowly equalize. Otherwise, a temperature change of a few degrees can shock your fish.

When acclimating a new fish, you can add a supplement such as Stress Coat to the water. This helps restore the protective slime coat, which can be damaged by stress or physical handling of the fish.

Additionally, you may take a sample of your aquarium water to the pet store in advance of your purchase to make sure the water parameters like pH are suitable for the fish you wish to buy.


Most aquarium fish subsist on a diet of pellets or flakes, but they may need more in order to thrive. Some fish need fresh plant matter, like zucchini, spinach, or algae. Others require extra protein – frozen or freeze-dried brine shrimp, tubifex worms, or bloodworms, for example.

Research the exact needs of your fish species. Then, provide them with supplements several times per week. You can also try species-specific fish foods, available for fish such as cichlids, bettas, or goldfish.


Having too many fish in a tank of a given size can tax the filtration system and diminish water quality. One inch of fish per gallon of water is a good rule of thumb, but some species require even more space.

Overcrowding can also lead to tank bullying – chasing, nipping of fins, and other stress-inducing harassment.

Observe the behavior of your fish. Is one bullying the others? Sometimes, the bully may be the most brightly colored male. You may need to move some of the fish to another tank, especially if males are fighting or constantly harassing the females. Another option is changing the ratio – one male to 6 or more females.


Reproduction can take a toll on your fish, most notably the female. This is especially true of mouth-brooding species, who don’t eat for several weeks while caring for young. Prepare breeding fish and help them recover by supplementing their diets before and after spawning.


Before purchasing a fish, look for signs of illness – drab color, clinched or tattered fins, white or black spots, red streaks, etc. Never introduce a sick fish to your community tank, and quarantine newcomers in a separate tank. If a fish in your community tank gets sick, remove it to a separate tank and provide appropriate medications.

Final Thoughts

If your fish look faded, try the following:

  • Check the water quality
  • Aerate the water
  • Check the temperature
  • Apply Stress Coat
  • Avoid overcrowding
  • Feed healthful supplements to help stressed fish recover
  • Look for signs of disease and treat them

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