How Many Angelfish in a 40 Gallon Tank (160 Liters) Should You Have? - "Angel fish" by R/DV/RS is licensed under CC BY 2.0.
How Many Angelfish in a 40 Gallon Tank (160 Liters) Should You Have? - "Angel fish" by R/DV/RS is licensed under CC BY 2.0.


When setting up an aquarium, one of the most common questions enthusiasts have is “how many angelfish in a 40 gallon tank (160 liters) can be kept without compromising their health and happiness?” This question is critical as it touches upon the balance between providing adequate space for these majestic creatures to thrive and avoiding overcrowding. Angelfish, known for their elegant fins and peaceful demeanor, require careful consideration of their environment to ensure they live a full and healthy life. The answer to this question is not merely a number but a reflection of understanding their space requirements, social behavior, and the overall dynamics of the aquarium ecosystem.

About Angelfish

Angelfish, scientifically known as Pterophyllum scalare, are one of the most recognized freshwater fish species in the aquarium hobby, beloved for their unique shape and graceful movements. Here’s an overview of their appearance and behavior:


  • Shape and Size: Angelfish are distinguished by their broad, laterally compressed bodies and triangular dorsal and anal fins, giving them a distinct arrowhead shape when viewed from the front. They typically grow up to 6 inches (15 cm) in length and can reach up to 10 inches (25 cm) in height, including their fins.
  • Color and Patterns: Angelfish come in a variety of colors and patterns, ranging from silver with black vertical stripes to more elaborate colorations including gold, marble, koi, and even albino. The wild-type angelfish display a silver body with four dark vertical stripes, one of which runs through the eye to help camouflage it from predators.
  • Fins: Their long, flowing fins are a hallmark of the species. These include the dorsal (top) and anal (bottom) fins that extend from the middle of the body to the tail, creating an elegant silhouette. The caudal (tail) fin is fan-shaped, contributing to their graceful swimming style.


  • Social Structure: Angelfish are generally peaceful but can exhibit territorial behavior, especially during breeding. They do well in groups, particularly in larger tanks where there’s ample space for each fish to establish its territory. However, care should be taken when mixing them with significantly smaller fish, as they might consider them food.
  • Breeding: They are known for their interesting breeding behavior. Angelfish form monogamous pairs and lay their eggs on a flat surface, such as a leaf or a piece of aquarium decor. Both parents are involved in guarding and tending to their eggs and fry, showing a high degree of parental care.
  • Feeding: In the wild, angelfish are omnivores, feeding on a diet of small invertebrates, crustaceans, and plant material. In the aquarium, they will accept a wide range of foods, including flakes, pellets, live, and frozen foods. Their feeding habits are not aggressive, but they are assertive eaters, often approaching food eagerly once they are accustomed to their environment.
  • Swimming Behavior: Angelfish are notable for their slow, graceful swimming movements. They use their large pectoral fins for precise movements and can maneuver with ease among aquarium plants and decorations. Their elegance is most apparent when they glide through the water, almost like birds through the air.

Angelfish are fascinating creatures that add beauty and intrigue to any freshwater aquarium. Their distinctive appearance and engaging behavior make them a favorite among aquarists. However, their care requires attention to tank conditions, diet, and social dynamics to ensure they thrive.

How Many Angelfish in a 40 Gallon Tank Should You Have?

Determining how many angelfish in a 40 gallon tank (160 liter) to keep, requires careful consideration of their size, age, and the overall tank environment. Here’s a refined approach to integrating your request:

When contemplating how many angelfish to house in a 40-gallon tank (160 liters), it’s important to distinguish between juveniles and adults due to their differing space requirements and behaviors.

For Young Angelfish

With smaller, young angelfish, you can initially accommodate a group of 5 to 6 in a 40-gallon (160 liter) setup. This allows the juveniles to grow and interact without immediate space constraints. However, vigilance is key; as these angelfish mature, their increasing size and territorial instincts may necessitate a reduction in numbers to avoid overcrowding and conflict.

For Adult Angelfish

When considering larger, adult angelfish, a 40-gallon tank (160 liter) can comfortably support up to 4 to 5 individuals. This calculation takes into account the need for each angelfish to claim its own territory while still maintaining a peaceful community setting. Managing the number of adults carefully helps in fostering a stable environment where the angelfish can exhibit natural behaviors without undue stress.

How Many Angelfish in a 40 Gallon Tank (160 Liters) Should You Have? - "Angel fish" by R/DV/RS is licensed under CC BY 2.0.
How Many Angelfish in a 40 Gallon Tank (160 Liters) Should You Have? – “Angel fish” by R/DV/RS is licensed under CC BY 2.0.

40 Gallon Tank (160 Liter) Setup for Angelfish

Setting up a 40-gallon tank (160 liters) for angelfish requires thoughtful consideration to create an environment that mimics their natural habitat, supports their health, and caters to their behavioral needs. Here’s a comprehensive guide on how to properly set up your tank:

  • Location: Choose a quiet location away from direct sunlight, drafts, and high-traffic areas to reduce stress on the fish.
  • Water Conditions: Angelfish prefer a pH of 6.5 to 7.5 and a temperature range of 76°F to 82°F (24°C to 28°C). Use a reliable heater and thermometer to maintain stable water conditions.
  • System Selection: Opt for a high-quality filtration system for maintaining clear water and removing waste products while providing gentle water flow that angelfish prefer.
  • Substrate: Use a fine, dark substrate to mimic the natural riverbeds and provide a contrast to the angelfish’s colors.
  • Plants: Incorporate live plants such as Amazon swords, Java ferns, and Anubias, which provide hiding spots and replicate their natural environment. Tall plants are especially appreciated, as they offer vertical spaces for angelfish to swim and hide. Artificial plants can also be a great option.
  • Decorations: Add driftwood, rocks, and caves to create a complex environment with plenty of hiding places and territories. Ensure that all decorations have smooth edges to prevent injury to the angelfish’s delicate fins.
  • Moderate Lighting: Provide moderate lighting to support plant growth without causing excessive algae development. LED aquarium lights with a timer can help simulate a natural day/night cycle.
  • Compatibility: Choose peaceful fish that are not small enough to be considered prey by adult angelfish. Good tank mates include larger tetras, dwarf cichlids (like rams), Corydoras catfish, and peaceful loaches.
  • Avoid Aggressive or Fin-nipping Fish: Avoid species known for aggressive behavior or fin-nipping, such as some barbs, as they can stress or injure angelfish.
  • Regular Water Changes: Perform regular water changes (about 20-25% weekly) to keep the water clean and free of toxins.
  • Testing Kits: Use water testing kits regularly to monitor ammonia, nitrite, nitrate, pH, and temperature levels.
  • Introduce Angelfish Properly: When introducing angelfish to the tank, acclimate them slowly to avoid shock from sudden changes in water parameters.
  • Balanced Diet: Feed a varied diet of high-quality flakes, pellets, frozen, and live foods to ensure proper nutrition and health.

Setting up a 40-gallon tank (160 liters) for angelfish with these considerations in mind creates a healthy, visually appealing environment that caters to the unique needs of these elegant fish. Remember, a well-planned tank not only supports the well-being of your angelfish but also enhances the overall aesthetic and enjoyment of your aquarium.


In conclusion, determining how many angelfish in a 40 gallon tank (160 liter) can comfortably live is essential for the well-being of these beautiful fish. A well-planned tank that takes into account the size and behavior of angelfish, along with the needs of any tank mates, can be a peaceful and healthy environment for up to 4 to 5 adult angelfish. Regular monitoring and adjustments may be necessary as the fish grow and their social interactions evolve. By prioritizing the needs of the angelfish and maintaining a balanced ecosystem, aquarists can enjoy the beauty and grace of these creatures in a harmonious aquatic setting.