Damselfish Tank Size and Care

With their vibrant colors, active nature, and unique personalities, it’s easy to see why damselfish are such popular fish for home saltwater aquariums. These fish display complex behaviors and require specific care regarding tank size, mates, water conditions, etc. This comprehensive guide will provide all the key information you need to stay happy and healthy.


Understanding Damselfish Behavior

Damselfish comprise over 250 species that are members of the family Pomacentridae. Most exhibit some common behavioral traits:

  • Territorial – Damsels claim certain areas or even entire tanks as their space. They aggressively defend these territories from other fish.
  • Aggressive – Their pugnacious nature earns them a reputation for nipping, chasing, and bullying more passive fish that invade their space.
  • Hardy – Damselfish tend to be hardy, durable fish that withstand various water conditions. This makes them good beginner fish.
  • Active – They spend most of their time swimming about briskly, not remaining still for long.
  • Smart – For fish, damsels show an unusually high intelligence and memory. They can be trained to recognize their owners.

Signs of Stress or Aggression

Watch for these indicators that your damsel may be stressed or showing unwelcome aggressive tendencies:

  • Darting rapidly around tank
  • Flaring gills
  • Nipping fins of other fish
  • Chasing tank mates away from its territory
  • Rubbing or flashing against objects
  • Hiding more than usual

Mitigating Aggressive Behavior

To curb problematic aggressive or territorial behaviors:

  • Provide lots of sheltered spaces and anchors for territories
  • Ensure tank is not overcrowded
  • Add dither fish to distract aggression
  • Feed foods high in fat and protein
  • Maintain stable water parameters
  • Use tank dividers to separate a bully fish if necessary

Now that we understand their temperament, let’s explore ideal tank sizes.

Ideal Tank Sizes for Different Damselfish

The following are minimum recommended tank sizes for popular damselfish species:

  • Azure Damselfish – 30 gallons
  • Blue Damselfish – 30 gallons
  • Domino Damselfish – 30 gallons
  • Humbug Damselfish – 30 gallons
  • Jewel Damselfish – 40 gallons
  • Sapphire Devil Damselfish – 125 gallons
  • Talbot’s Damselfish – 29 gallons
  • Threespot Damselfish – 30 gallons
  • Twobar Damselfish – 29 gallons

General Damselfish Tank Size Guidelines

  • Nano Fish: 15-30 gallons
  • Medium Fish: 30-65 gallons
  • Large/Aggressive Fish: 90-250+ gallons

Bigger is always better when it comes to damsels. A larger tank dilutes aggression and allows you to add more dither fish to spread out bullying behaviors.

How Many Damselfish Per Tank Size

Damselfish should be kept singly or in small groups, depending on species and tank size:

10 Gallon Tank

Not suitable for damselfish.

20 Gallon Tank

Capacity for 1-2 small, peaceful species like Twobar or Sapphire.

30 Gallon Tank

Space for 1-2 medium semi-aggressive species like Humbug or Jewel.

50 Gallon Tank

A 50 gallon tank can house 3-4 damselfish depending on species. Mix peaceful and aggressive types.

100+ Gallon Tank

Larger tanks can accommodate small groups or pairs of larger damselfish like Sergeant Majors.

Choosing the Right Tank Mates

Tank mates should be selected carefully to minimize aggression:

Good Tank Mates

  • Clownfish
  • Large angelfish
  • Tangs
  • Surgeonfish
  • Puffers
  • Groupers
  • Rabbitfish
  • Lionfish
  • Blennies
  • Gobies
  • Wrasses
  • Hawkfish
  • Banggai cardinal

Poor Tank Mates

  • Small goby species
  • Seahorses
  • Pipefish
  • Shrimp
  • Crabs
  • Snails
  • Clams
  • Corals
  • Feather dusters

Avoid passive, ornate, or shrimp-like creatures that will draw damsel aggression. Bottom dwellers are prone to being bullied.

Special Considerations for Specific Damselfish

When selecting your species, be aware of any special care requirements:

  • Size – Some damsels like Sergeant Majors reach 6 inches, requiring larger tanks
  • Aggression – Bicolor damsels are one of the most aggressive species and need ample space
  • Reef Safe – Chromis, azure, and ambon damsels do well in reef tanks. Sergeant majors nip at coral.
  • Care Level – Hardier species like Blue Chromis make good beginner fish. More advanced fish like Pyramid Butterflyfish require experienced keepers.

Research the particular damsel species you are interested in before obtaining one.

Are Damselfish Reef Safe?

Most damselfish species can be considered reef safe to some degree. Some exceptions are:

  • Sergeant Majors
  • Three Stripe Damsels
  • Domino Damsels

These tend to nip at stony corals like Acropora or Montipora. Slow growing soft corals also struggle with damsels.

To keep damsels in reef tanks:

  • Provide plenty of rockwork for territories
  • Feed well to reduce nipping behavior
  • Add before corals or sessile invertebrates
  • Select only peaceful community species like Chromis or Ambon Damsels

With caution, the right species selection, and proper introduction, many damselfish thrive in reef tanks.

Damselfish Species Tank: Pros and Cons

Keeping a tank with only damselfish can work well since they have similar care needs. Consider the following:


  • No compatibility or aggression issues
  • Can keep more damsels together
  • Simple diet and water parameter needs
  • Interesting behaviors and interactions to observe
  • Healthy competition and activity in the tank
  • Visually appealing groups of colorful fish


  • Lack of diversity – only one family of fish
  • Potential aggression without dither fish to curb bullying
  • Messier tank without algae grazers or detritivores
  • Missing different behaviors and swim patterns
  • More prone to disease outbreaks
  • Less overall visual interest

A damsel-only tank can thrive with proper stocking levels and tank size. But most aquarists prefer adding other family groups as well.

Additional Tips for Keeping Damselfish

Here are a few more pointers for successfully keeping damselfish:

  • Add damsels last when stocking a tank to reduce territorial issues
  • Provide plenty of strong water movement and oxygenation
  • Maintain stable water parameters like pH and salinity
  • Offer a varied diet with marine flakes, pellets, shrimp, mysid, and spirulina
  • Include multiple cleaning crews like snails, shrimp, and sea stars to handle waste
  • Arrange rockwork and anchors to break up sightlines and allow territories
  • Limit handling and interaction with damsels once settled in tank

By understanding damsel behavior and caring for their needs, your tank will have a vibrant personality and splash of color from these feisty fish. Provide a proper environment and compatible tank mates, and damselfish will thrive.


From selecting the ideal tank size to choosing appropriate tank mates, successfully keeping damselfish requires forethought and understanding their territorial nature. Follow the recommendations in this guide, and you’ll be well equipped to give your damselfish everything they need to stay healthy and show off their lively behaviors in a home aquarium habitat. With their dazzling colors and activity levels, damselfish will quickly become a favorite!