Guppy Tails Fading: Why?

why are my guppy

Guppies are typically very colourful fish, so it can be worrying when their tails start to lose colour. There are many reasons why this might be happening, including stress, poor water quality, a new environment, bullying from other fish, or a poor diet. Guppies can also lose colour due to natural factors such as ageing and genetics. If your guppy is losing its colour, it's important to take steps to address the issue, such as improving water quality, reducing stress, and ensuring a proper diet.

Characteristics Values
Cause of tail color loss Stress, poor water quality, harsh lighting, lack of nutrients, underlying health conditions, artificial colors, aging, genetics, sleep, wrong male-to-female ratio, new environment, fish bullying, overcrowded aquarium, water temperature, water toxins
Signs of stress in guppies Loss of appetite, lack of energy, unusual swimming patterns
Water parameters to measure Temperature, ammonia, nitrite, nitrate, pH, KH, GH
Ideal water parameters Temperature: 72-82°F (22-28°C), Nitrate: less than 25 ppm
Treatments for common diseases Ich: raise tank temperature, add aquarium salt, use medication; Fin rot: ensure water temperature is 72°-82° F (22°-28° C), use erythromycin antibiotic, remove fish waste; Fungal infections: use a 1% Phenoxethol solution or Chloromycetin



Guppies are susceptible to stress, which is one of the most common causes of colour fading in these fish. Stress can be caused by various factors, including:

  • Bullying tank mates: Guppies should not be kept with aggressive fish such as tiger barbs, which will chase and nip at their fins. Male guppies can also become aggressive towards each other, especially when there are not enough females in the tank.
  • Harsh lighting: Guppies may become stressed due to harsh or bright lighting conditions in their tank.
  • Overcrowding: Keeping too many guppies or other fish in a small tank can lead to stress and territorial aggression.
  • New environment: Introducing guppies to a new tank or a new group of tank mates can be stressful and shocking for them.
  • Poor water quality: Insufficient water quality, such as wild temperature fluctuations or a build-up of toxins like nitrates, nitrites, and ammonia, can induce stress and even poison guppies.
  • Underlying diseases: Certain diseases and infections, such as ich, fin rot, or Saprolegnia fungus, can cause stress and colour loss in guppies.
  • Lack of nutrients: A poor diet that does not meet the nutritional needs of guppies can contribute to colour loss over time.
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Poor water quality

Guppies require specific water parameters, including a stable temperature of 72° to 78°F (22°-28°C), a pH of 7.0 or higher, and decent quantities of minerals like magnesium and calcium. Poor water quality can lead to a spike in toxins such as nitrates, nitrites, and ammonia, which can be fatal to guppies.

To maintain good water quality, regular water changes are necessary. It is recommended to change 15-20% of the water weekly and vacuum the substrate to remove any dead organic matter. Leftover food and dead plants or animals can cause a build-up of ammonia, which is harmful to guppies.

Additionally, testing the water for toxins is essential. API Aquarium Test Kits can help measure toxins like ammonia, nitrites, nitrates, and phosphates. By maintaining the right water parameters and regularly cleaning the tank, guppy owners can ensure their fish stay healthy and colourful.

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Underlying disease

Guppies are usually resilient and colourful, but sometimes their tails lose colour. This can be due to underlying diseases such as:


Ich, or white spot disease, is caused by the parasite *Ichthyophthirius Multifiliis*, which enters the fish through the gills and sticks to the stomach, fins, and gills. It is often caused by poor water quality, especially high concentrations of nitrite, nitrate, and ammonia. It can also be caused by stress from overpopulation, inadequate nutrition, or abrupt changes in temperature or water chemistry. Symptoms include tiny white dots all over the body and fins, and redness on the body and fins. In extreme cases, Ich can cause death.

Fin Rot

Fin rot is caused by a microbial infection, usually due to poor water quality, such as high levels of nitrite, nitrate, and ammonia. It can also be caused by physical damage to the fins, inadequate nutrition, or other underlying medical conditions that compromise the immune system. Symptoms include damaged tails and fins, tissue deterioration, tattered and flaked fins and tails, and faded or rotten ends on the fins.

Swim Bladder Disorder

Swim bladder disorder is a condition that affects the swim bladder, a sac near the fish's backbone that regulates buoyancy. It can be caused by overeating, constipation, and biological abnormalities. Other causes include physical harm, exposure to pesticides or harmful substances, and certain pathogens or microbial species. Symptoms include difficulty swimming, floating at the top or sinking to the bottom of the tank, incoordination or a fractured spine, and a distended abdomen.

Mouth Fungus

Mouth fungus, or cotton mouth/wool infection, is caused by the fungal pathogen *Saprolegnia*, which infects the fish's mouth and gills. It is an opportunistic illness that tends to affect fish that are already stressed or have weak immune systems. Symptoms include white or grey ulcerations on the body, fins, and head, difficulty swimming, skin irritation on the fins and body, and white cotton-like cysts on the lips, gills, and fins.


Dropsy is a disorder that causes the fish's body to fill with fluid. It can be caused by respiratory diseases, viral infections, poor water quality, and internal organ damage. Symptoms include pinecone-shaped scales, reddish undertones on the fins and body, and swimming abnormalities.

If you suspect your guppy is suffering from any of these diseases, it is important to take action. Consult a veterinarian or experienced aquarist, improve water quality, ensure your fish has a well-rounded diet, and avoid overcrowding.


Poor diet

Guppies are typically vibrant and colorful, but they can lose their color due to various reasons, including poor diet. A poor diet can have a direct impact on the coloration of guppies, and it is crucial to ensure they receive adequate nutrition to maintain their vibrant tails.

Guppies are known for their diverse appetite, and it is essential to provide them with a varied and nutritious diet. A common mistake is feeding them solely flakes or pellets, which may not provide all the necessary nutrients. This inadequate diet can lead to a lack of essential nutrients, which will eventually affect their size and color. Therefore, it is crucial to include a variety of food items in their diet, such as bloodworms, vegetables, algae, brine shrimp, and mosquito larvae.

In the wild, guppies have a diverse diet that includes algal remains, aquatic insect larvae, diatoms, detritus, invertebrates, zooplankton, plant fragments, and mineral particles. Captive guppies, on the other hand, thrive on nutrient-dense foods like frozen bloodworms, tubifex worms, and mosquito larvae. It is important to mimic their natural diet as closely as possible to ensure they receive the necessary nutrients.

Additionally, guppies should be fed a color-inducing diet rich in certain pigments to enhance their coloration. For example, frozen crustaceans are rich in pigments that contribute to orange, yellow, and red colors in guppies. By including these foods in their diet, you can help intensify their natural colors.

It is also important to note that overfeeding should be avoided, as it can lead to health issues for guppies. Adult guppies only need to eat once or twice a day, and their meals should be appropriately portioned.

In summary, a poor diet can directly impact the color of guppies, and it is essential to provide them with a varied and nutritious diet that includes essential nutrients and color-enhancing ingredients. By doing so, you can help maintain the vibrant tails of your guppies and ensure their overall health and well-being.


Natural factors

Guppies are usually very colorful, but they can lose their color due to several natural factors. Here are some of the most common reasons:


As guppies age, their bodies undergo various changes, including a decrease in the density of chromatophores—the cells responsible for pigmentation. As a result, older guppies may have paler skin and less vibrant colors than younger ones. This is a natural process that fish go through as they mature, and there is not much that can be done to prevent it.

Genetics and Gender

The colorful appearance of male guppies is due to specific genetic factors. Male guppies have chromosomes that exchange genes only at the tips, allowing them to receive and retain bright colors, especially orange shades that female guppies find attractive. On the other hand, female guppies have duller brown shades because they lack these color-bearing chromosomes.


It is natural for guppies to appear paler when they are sleeping. However, they will regain their original color once they wake up.

Diet and Nutrition

Guppies require a diverse and nutritious diet to maintain their bright colors. In the wild, they feed on various items such as algal remains, aquatic insect larvae, diatoms, and plant fragments. In captivity, they thrive on nutrient-dense foods like brine shrimp, bloodworms, and mosquito larvae. If they are fed an inadequate diet, such as solely flakes or pellets, their color may fade over time due to a lack of essential nutrients.

Lighting Conditions

The lighting in your aquarium can also impact the perceived color of your guppies. Guppies with shimmery tones will glow under bright lights, while those with red, orange, yellow, and brown tones will be enhanced by warm-spectrum lighting.

Frequently asked questions

Guppies' tails can lose color due to various reasons, including stress, poor water quality, underlying health conditions, and lack of proper nutrients.

Guppies exhibit several signs when they are under stress, such as loss of appetite, lack of energy, and unusual swimming patterns, like moving randomly or in a circular motion.

Some common diseases that affect guppies include ich, which causes white spots, fin rot, and Saprolegnia fungus, which can discolour the scales, fins, and tail.

Guppies have a broad appetite and should be fed a diverse diet, including bloodworms, vegetables, algae, brine shrimp, and plant matter.

The ideal water parameters for guppies are a temperature of 72-82°F (22-28°C), nitrate levels below 25 ppm, and regular testing to ensure stable ammonia, nitrite, and pH levels.

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