Angelfish Water Parameters: Everything You Need To Know

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If you’re just getting started with Angelfish, you might be wondering about their water requirements.

What’s the ideal temperature for them? How about pH and water hardness levels? And what’s the deal with ammonia, nitrate, and nitrites?

Are Angelfish particularly sensitive to these parameters?

I’ll cover all these topics in this article, providing you with all the information you need. Let’s get started.

Also Read: Angelfish Tank Setup

Ideal Water Parameters for Angelfish

Angelfish thrive best in soft, slightly acidic to neutral water conditions. Maintaining specific water parameters ensures their health, colors, and optimal breeding conditions.

  • pH Levels: Angelfish prefer a pH between 6.5 to 7.5. This slightly acidic to neutral range mimics their natural Amazonian habitat.
  • Temperature: Ideal temperatures range from 76°F to 82°F. Stable temperatures within this range promote metabolism and disease resistance.
  • Hardness: Angelfish flourish in soft to moderately hard water, with a dGH of 3 to 8. This simulates the soft waters of their native environments.
  • Water Cleanliness: Ammonia, nitrite, and nitrate levels should be closely monitored. Keep them at 0 ppm for ammonia and nitrite, and below 20 ppm for nitrate.

The tools I use for measurements are:

Optimal Temperature for Angelfish

The optimal temperature for Angelfish lies between 76°F to 82°F, ensuring their well-being and vibrant colors.

Properly regulating the tank’s temperature is crucial for their overall health.

1. How to Increase the Temperature in an Angelfish Tank

Upgrading or adjusting your aquarium heater can achieve the desired increase in temperature.

  • Adjust the Heater: Most aquarium heaters feature a dial; carefully turn it up by 1°F each day until reaching the desired 76-82°F range. I personally chose the Fluval E300 Advanced Heater (link to Amazon)
  • Higher Wattage Heater: For sizable tanks like 50 gallons, a heater ranging from 150 to 200 watts is recommended; larger aquariums might demand even more power.
  • Tank Positioning: Opt for placing the tank closer to sunlight or warmer areas of the room, but ensure you consistently monitor to avoid potential overheating issues.

Also Read: Do Angelfish Need A Heater?

2. How to Decrease the Temperature in an Angelfish Tank

Effective cooling methods and careful equipment adjustments can lower excessive tank temperatures.

  • Reduce Heater Setting: Systematically dial down the heater’s thermostat by 1°F daily until comfortably resting within the optimal 76-82°F zone.
  • Use a Fan: Strategically placing a fan to blow across the tank’s surface encourages evaporation, which naturally cools the water.
  • Change Water: Thoughtfully replace about 10-15% of the tank water with slightly cooler water; this method cools efficiently without shocking your Angelfish.

Also Read: Angelfish Temperature Guide

Best pH Levels for Angelfish

For Angelfish to truly flourish, maintaining a pH level between 6.5 and 7.5 is crucial.

This slightly acidic to neutral range mirrors their natural Amazonian habitat, which they’ve evolved to thrive in.

1. How to Raise the pH for Angelfish

Raising the pH can be achieved with careful additions to your tank environment.

  • Baking Soda: Dissolving a small amount of baking soda (1 teaspoon for every 5 gallons) in tank water can effectively raise the pH, but do so gradually.
  • Crushed Coral or Limestone: Introducing crushed coral or limestone into the filter or substrate will steadily release calcium carbonate, increasing the pH over time.
  • Aeration: Enhancing the tank’s aeration can drive off excess CO2, which can help to gently elevate the pH levels. The Hygger Aquarium Air Stone (link to Amazon) is highly effective for this purpose.

2. How to Lower the pH for Angelfish

Lowering the pH requires introducing elements that increase acidity.

  • Peat Moss: Introducing peat moss to the filter can gently acidify the water, lowering the pH. Monitor closely to avoid sharp changes.
  • Driftwood: Natural tannins from driftwood not only tinge the water with a soft brown hue but also subtly decrease the pH.
  • Commercial pH Adjusters: Available at aquatic stores, these specialized solutions can be added following product guidelines to achieve desired pH levels. The API PROPER pH 7.0 (link to Amazon) is an excellent starting point.

Also Read: Best pH Level For Angelfish

Ideal Water Hardness for Angelfish

Angelfish thrive best in soft to moderately hard water, typically within a dGH range of 3 to 8. 

Ensuring the appropriate hardness level not only promotes their overall well-being but also imitates their natural Amazonian water conditions.

1. How to Boost the Water Hardness

Increasing water hardness can be attained with specific additives and media.

  • Crushed Coral or Limestone: Incorporating these into your substrate or filter gradually releases calcium and magnesium, effectively hardening the water over time.
  • Commercial Hardness Increasers: Specialty products, available at aquarium stores, can elevate hardness. It’s crucial to follow the provided guidelines and dose accordingly.
  • Baking Soda: A careful addition of baking soda (1/2 teaspoon per 10 gallons) can raise both the pH and general hardness, but always introduce it slowly.

2. How to Make the Water Softer for Angelfish

Reducing water hardness can be achieved with select methods and materials.

  • Reverse Osmosis (RO) Water: Mixing your tap water with RO water is an effective way to soften it. The ratio can be adjusted based on the desired hardness.
  • Peat Moss: Adding peat moss to your filter not only lowers pH but also releases tannins that naturally soften the water, providing an Amazon-like environment.
  • Water Softening Pillows: Found at aquatic stores, these resin-filled pouches placed in filters swap calcium and magnesium ions for sodium, softening water. My recommendation: API Water Softener Pillow (link to Amazon).

Also Read: Do Angelfish Like Hard Or Soft Water?

Ammonia, Nitrate, and Nitrite for Angelfish

For Angelfish, maintaining low levels of ammonia, nitrate, and nitrite is fundamental for their health and vibrancy.

Specifically, ammonia and nitrite levels should always be 0 ppm, while nitrates should be kept below 20 ppm to avoid stress and disease.

  • Ammonia’s Impact: Even small traces (0.25 ppm) can harm angelfish, leading to stress, weakened immunity, and potential fatalities.
  • Nitrite Dangers: Levels above 0.5 ppm can reduce oxygen in the blood, causing “brown blood disease” in angelfish.
  • Nitrate Levels: While less toxic than the others, prolonged exposure above 40 ppm can harm angelfish; aim for below 20 ppm.
  • Regular Testing: Using aquarium test kits weekly helps monitor these parameters, ensuring a safe environment for your angelfish.

Are Angelfish Sensitive to Water Changes?

Yes, Angelfish are sensitive to abrupt water changes. Drastic shifts in water chemistry or temperature can stress them and lead to health complications.

  • Stress Signs: Rapid gill movement, loss of color, or unusual swimming are indicators of water-change-induced stress in angelfish.
  • Gradual Changes: When changing water, ensure the new water’s parameters and temperature closely match the tank’s to avoid shocking the fish.
  • Acclimation Process: If introducing new angelfish, it’s pivotal to slowly acclimate them to the tank’s conditions over an hour or more.
  • Consistency is Key: Regular, smaller water changes (15-20% weekly) are more beneficial and less stressful than infrequent, large changes.

Also Read: Angelfish Tank Size

Do Angelfish Need Salt Water?

No, not all Angelfish require saltwater, but there are different species.

Freshwater angelfish are native to the Amazon River Basin, whereas marine angelfish are saltwater creatures from tropical oceans.

  • Freshwater Habitat: Freshwater angelfish come from the Amazon’s rivers and streams, where they thrive in soft, slightly acidic conditions without marine salt.
  • Marine Angelfish: Found in tropical and subtropical oceans, these angelfish need saltwater with specific gravity, temperature, and pH levels suited for marine life.
  • Salt for Treatment: While freshwater angelfish don’t live in saltwater, a mild salt solution can help treat some diseases or parasites they might encounter.
  • Tank Setup Variance: Freshwater angelfish tanks should have soft, slightly acidic water with dense vegetation. In contrast, marine angelfish require a saltwater setup with live rock and suitable marine tankmates.

Are Angelfish Sensitive to pH?

Yes, Angelfish are sensitive to drastic pH shifts. While they can adapt to a range of pH levels, sudden changes can cause them undue stress and potential health complications.

  • Natural Environment: In their Amazonian habitat, angelfish experience slightly acidic waters, typically with a pH of 6.5 to 7.5.
  • Adaptability Limit: While angelfish can adjust to varying pH levels, rapid swings in either direction can be harmful.
  • Symptoms of pH Stress: Signs like erratic swimming, labored breathing, or loss of color can indicate pH-induced stress in angelfish.
  • Steady Adjustments: If you need to adjust the pH in an angelfish tank, do so gradually over several days to allow them to acclimate without distress.

Is 20 ppm Nitrate Too High?

For many aquarium inhabitants, a nitrate level of 20 ppm is considered to be on the higher end of acceptable.

While some fish can tolerate it, consistently elevated nitrate levels can lead to health issues over time.

  • General Rule: For most freshwater tanks, keeping nitrates below 20 ppm is advised to ensure the well-being of the aquatic life.
  • Stress Factor: Elevated nitrate levels can cause stress, reducing a fish’s immunity and making them more susceptible to diseases.
  • Plant Growth: In planted tanks, while plants can absorb nitrates, excessively high levels can lead to unwanted algae blooms.
  • Regular Monitoring: Using a nitrate test kit weekly can help track and manage nitrate levels, ensuring a healthier environment for fish.


For those of you who are just skimming through, here’s a short summary:

  • Angelfish thrive in soft, slightly acidic to neutral water conditions with a pH of 6.5 to 7.5, mirroring their Amazonian habitat.
  • The ideal temperature for Angelfish is between 76°F to 82°F; stability within this range promotes their metabolism and disease resistance.
  • Angelfish are sensitive to abrupt changes in water parameters, with signs of stress including rapid gill movement and loss of color.
  • Not all Angelfish require saltwater; freshwater angelfish hail from the Amazon and need soft, slightly acidic conditions without marine salt.
  • Elevated nitrate levels, such as 20 ppm, can be stressful for many fish and can lead to health complications over time.