Why Is My Angelfish Turning Black? (5 Practical Solutions)

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Angelfish are a popular choice for home aquariums because they look great and get along with many other fish.

But sometimes, they can cause concern. That’s how I felt when one of my angelfish started turning black.

Not sure what to do, I started researching. I found out there are different reasons for this color change, and each has its own solution.

Let’s dive right into it.

Is It Normal for Angelfish to Turn Black?

No, in most cases, it isn’t normal for angelfish to turn black; this change is often a sign of stress, poor water conditions, or illness.

However, a few instances could be attributed to genetic factors and natural coloration.

It’s crucial to observe for additional symptoms to determine if the color change indicates a health issue.

Why Is My Angelfish Turning Black?

If your angelfish is becoming black, there could be different causes to think about. Here are some things to keep in mind:

1. Stress or Environmental Changes

Angelfish are highly sensitive to their environment, and stress or significant changes in their surroundings can lead to color changes, including turning black.

This stress can be caused by various factors ranging from tank mates to abrupt shifts in the aquarium’s conditions.

  • Environmental Shifts: Sudden changes in water temperature, pH levels, or lighting can cause stress in angelfish, leading to blackening as a response.
  • Tank Dynamics: Introduction of new fish or aggressive tank mates can stress angelfish, resulting in them turning black as a sign of distress.
  • Other Stress Signs: Look for signs like reduced appetite, hiding more than usual, or erratic swimming, which indicate stress in angelfish.

Also Read: Stress In Angelfish

2. Genetic Traits or Aging

In some cases, turning black can be a natural aspect of an angelfish’s genetic makeup or a sign of aging.

Certain angelfish species or individuals naturally develop darker coloration as they mature.

  • Genetic Factors: Some angelfish have a genetic predisposition to darken with age, which is a normal part of their development.
  • Aging Process: As angelfish age, they may undergo color changes, including turning black, which is a natural aspect of their lifecycle.
  • Identifying Aging: Along with color changes, older angelfish may show signs like slower movement and reduced agility.

3. Disease or Parasitic Infection

Diseases or parasitic infections can lead to angelfish turning black, often as a reaction to the ailment affecting their body.

This change in color may reflect the fish’s immune system actively fighting the infection.

  • Disease Impact: Conditions like bacterial infections or parasites can disrupt the normal state of angelfish, resulting in a darker appearance.
  • Parasitic Effects: Parasites, whether internal or external, can cause discomfort in angelfish, which might manifest in changes in their color.
  • Symptoms of Illness: Additional signs such as clamped fins, white spots, lethargy, or abnormal swimming patterns are key indicators of illness.

4. Poor Water Quality

Poor water quality is a major factor that can negatively affect angelfish, potentially causing them to turn black.

  • Toxic Conditions: High levels of ammonia, nitrites, and nitrates are harmful and can lead to health issues in angelfish, including changes in coloration.
  • Filtration Issues: Inadequate filtration can compromise water quality, impacting the health of angelfish and possibly leading to color changes.
  • Signs of Poor Water: Look for symptoms like gasping at the surface or lethargy, which are indicative of poor water quality.

5. Nutritional Deficiencies

Nutritional deficiencies in angelfish can result in various health problems, including a change in coloration.

  • Dietary Impact: A diet lacking essential vitamins and minerals can lead to health issues in angelfish, manifesting as changes in their color.
  • Lack of Variety: A diet that doesn’t vary much can lead to deficiencies, which might contribute to the angelfish turning black.
  • Additional Nutritional Signs: Indicators such as faded colors, listlessness, or a reduced appetite can point towards nutritional issues.

Also Read: Why Is My Angelfish Not Growing?

How to Treat Angelfish That Turn Black

Here’s how to deal with some of the main reasons why angelfish might turn black:

1. Improve Water Quality and Stability

Maintaining high water quality is crucial in treating angelfish that have turned black.

Regular monitoring and adjustments to the water conditions can help restore and maintain the fish’s health.

  • Regular Water Testing: Keep pH within 6.5-7.5, ammonia and nitrite near zero, and nitrate below 20 ppm for a healthy angelfish environment. Use a reliable test kit such as the API Freshwater Master Test Kit (link to Amazon).
  • Consistent Water Changes: Perform regular water changes, ideally 20-25% weekly, to remove toxins and replenish essential minerals in the aquarium.
  • Effective Filtration: Use a high-quality filter suited to your tank’s size to keep the water clean and reduce the buildup of harmful substances.
  • Temperature Stability: Maintain a consistent water temperature, preferably between 76-82°F, as fluctuations can stress angelfish and worsen their condition.

Also Read: Angelfish Water Parameters

2. Reduce Stress Factors in the Aquarium

Reducing stress factors is essential for the well-being of angelfish, especially if they are showing signs of stress like turning black.

Creating a peaceful and stable environment in the aquarium can significantly improve their health and coloration.

  • Adequate Space Allocation: Ensure at least 10 gallons of water per angelfish, as overcrowding can lead to stress and aggression among fish.
  • Environmental Enrichment: Add plants, hiding spots, and decorations to provide shelter and reduce stress, creating a more natural and comforting habitat.
  • Consistent Routine: Establish a regular feeding and maintenance routine to avoid sudden changes that can stress your angelfish.
  • Harmonious Tank Mates: Choose tank mates carefully; avoid aggressive or overly active fish that can intimidate or harass angelfish.

For example, opt for peaceful and gentle species, such as:

  • Neon Tetras (Paracheirodon innesi)
  • Mollies (Poecilia spp.)
  • Platies (Xiphophorus maculatus)
  • Dwarf Gourami (Trichogaster lalius)
  • Corydoras Catfish (Corydoras spp.)
  • Rummy-nose Tetra (Hemigrammus rhodostomus)
  • Bristlenose Pleco (Ancistrus spp.)

On the other hand, avoid aggressive fish like:

  • Betta Fish (Betta splendens)
  • Goldfish (Carassius auratus)
  • Common Pleco (Hypostomus plecostomus)
  • African Cichlids (Cichlidae family)
  • Tiger Barb (Puntigrus tetrazona)
  • Red-tailed Shark (Epalzeorhynchos bicolor)
  • Jack Dempsey (Rocio octofasciata)

Also Read: Angelfish Tank Mates

3. Treat Diseases and Parasitic Infections

Addressing and treating any diseases or parasitic infections is critical in reversing the blackening of angelfish.

Accurate diagnosis and appropriate treatment are key to their recovery.

  • Prompt Disease Identification: If you suspect a disease, consult with a vet or an aquatic specialist for an accurate diagnosis and treatment plan.
  • Quarantine Affected Fish: Isolate affected angelfish in a separate tank to prevent the spread of disease and allow for targeted treatment.
  • Medication Administration: Use medications specifically designed for treating the identified disease or parasite, following dosage instructions carefully.
  • Observation Post-Treatment: After treatment, closely monitor the angelfish for improvements and ensure the disease does not recur.

A good starting point would be to use over-the-counter products like Seachem PolyGuard (link to Amazon), which treats a wide range of bacterial, fungal, and parasitic infections.

Also Read: Angelfish Diseases

4. Provide Balanced and Nutritious Diet

A balanced diet is fundamental to the health of angelfish, and dietary improvements can help in cases where blackening is related to nutritional deficiencies.

  • Varied Diet Inclusion: Feed a mix of high-quality flakes, pellets, frozen, and live foods to ensure a balanced intake of nutrients.
  • Regular Feeding Schedule: Feed small amounts 2-3 times a day instead of one large feeding to mimic natural eating patterns and improve digestion.
  • Supplemental Nutrients: Consider adding vitamin and mineral supplements to the diet, especially if the primary food source lacks variety. I personally use this Seachem Nourish (link to Amazon).
  • Observation of Eating Habits: Regularly observe feeding behaviors to ensure all fish are eating well and adjust the diet as needed for picky eaters.

Also Read: How To Feed Angelfish

5. Adjust Tank Conditions to Suit Specific Genetic Traits

For angelfish turning black due to genetic traits or natural aging, adjusting the tank conditions to better suit their specific needs can be beneficial.

  • Research Specific Needs: Understand the specific requirements of your angelfish breed, as some may prefer different water parameters or environments.
  • Customized Habitat: Adjust lighting, water flow, and decorations to mimic the natural habitat of your specific angelfish species.
  • Tank Mate Consideration: Choose tank mates that are compatible with the specific behaviors and needs of your angelfish breed.
  • Regular Health Monitoring: Keep a close eye on your angelfish for any signs of stress or discomfort, adjusting tank conditions as needed to ensure their well-being.

Is My Angelfish’s Black Coloration Natural?

Your angelfish’s black coloration can be natural, especially if it’s a trait of their specific breed or a result of aging.

It’s important to distinguish between natural coloration and color changes due to stress or health issues.

  • Breed Specificity: Research your angelfish breed; some, like Black Lace or Smokey, naturally exhibit darker or black coloration as part of their genetic makeup.
  • Consistency Over Time: If the black coloration has been consistent since young adulthood without any signs of distress, it’s likely a natural trait.
  • Absence of Stress Behaviors: Natural black coloration is typically accompanied by normal behavior—active swimming, regular eating, and interaction with other fish.
  • Check for Symmetry: Natural coloration patterns are usually symmetrical on both sides of the angelfish’s body, whereas stress-induced changes might be uneven.

For instance, here are some angelfish species that are very likely to turn black due to natural traits:

  • Black Lace Angelfish
  • Smokey Angelfish
  • Marble Angelfish
  • Black Veil Angelfish
  • Chocolate Angelfish
  • Zebra Angelfish
  • Black Ghost Angelfish
  • Midnight Angelfish
  • Black Hybrid Angelfish
  • Silver Black Angelfish

What Other Signs Should I Look For If My Angelfish Changes Color?

When your angelfish changes color, it’s crucial to observe for other signs that might indicate a serious underlying issue rather than natural coloration.

Changes due to health problems are often accompanied by behavioral or physical symptoms.

  • Behavioral Changes: Watch for unusual behaviors such as lethargy, hiding more than usual, loss of appetite, or aggressive interactions with tank mates.
  • Physical Symptoms: Apart from color changes, signs like clamped fins, white spots, or ulcers can indicate health issues like diseases or parasitic infections.
  • Rapid Color Change: A sudden and rapid change in coloration, especially if it’s uneven, can be a sign of stress, poor water quality, or illness.
  • Eating Patterns: Monitor the angelfish’s eating habits; a decline in appetite or refusal to eat is often a sign of stress or illness.

How Often Should I Monitor My Angelfish’s Coloration?

I would recommend keeping a close eye on your angelfish’s coloration regularly, ideally daily when you feed them.

Sudden or gradual changes in color can be key indicators of their health or stress levels.

By consistently observing their coloration, you’ll be better equipped to catch any potential issues early and maintain their well-being.

Also Read: Angelfish Turning White


For quick readers, here’s a short summary:

  • Angelfish turning black is often abnormal, signaling stress, poor water conditions, or illness, though some blackening can be due to genetics or aging.
  • Environmental factors like sudden water changes, stressful tank dynamics, or inadequate filtration can lead to stress-induced blackening in angelfish.
  • Diseases, parasitic infections, and nutritional deficiencies can cause angelfish to turn black, alongside other symptoms like lethargy or clamped fins.
  • Remedies include improving water quality, reducing stress, treating diseases, providing a balanced diet, and adjusting tank conditions for specific breeds.
  • Regular monitoring of the angelfish’s color and behavior is crucial for early detection of stress or health issues, with natural black coloration being symmetrical and consistent.