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CardinalFish Care Sheet

Developed with and approved by a qualified veterinarian.

Includes a variety of cardinalfish, including:  

  • Pajama cardinal
  • Banggai cardinal
  • Flamefish cardinal
  • Black cardinal 
  • Twospot cardinal 
  • Blue-eyed cardinal 
  • Yellow-stripe cardinal 
  • Red spot cardinal


Scientific name: Sphaeramia nematoptera, Pterapogon kauderni, Apogon maculatus, Apogonichthyoides melas,  Apogon pseudomaculatus, Zoramia leptachantha,  Apogon cyanosoma, Apogon parvulus

Cardinalfish have two distinct dorsal fins and can be found around the world. These slower-moving nocturnal fish make excellent additions to large community aquariums. Most species are recommended for beginning marine aquarists.

Typical appearance and behavior

  • Some peaceful species may be kept in small groups; different species should not be mixed
  • Although nocturnal (active at night), cardinalfish can become used to daytime feeding and activity
  • May become aggressive toward individuals of the same species; should be kept in groups of five or more
  • Some species are mouth brooders and have been successfully bred by aquarists


Care Difficulty Easy
Average Life Span Up to 15 years with proper care, depending on species
Average Adult Size 1-9+ inches long, depending on species
Diet Carnivore
Minimum Habitat Size 5+ gallons for a single cardinalfish, depending on species
Water Temperature 74-80°F
Specific Gravity 1.020-1.025


Habitat size

  • Water health - Provide proper filtration to ensure optimal water quality to help maintain health. Slow to moderate water circulation, based on species, should be provided to mimic water currents found in the cardinal's natural habitat. Stable water quality (pH, ammonia, nitrate, nitrite) and water temperature are critical to the health of aquatic life. If you are unsure of your water quality, bring a sample to Petco for free testing. The addition of a protein skimmer can aid with maintaining great water quality and high dissolved oxygen levels. An aquatic heater should be used to stabilize water temperature, ensuring it does not fluctuate more than +/-2 degrees in a 24-hour period. The specific gravity should remain stable. Do not allow specific gravity to fluctuate more than +/-0.001 in a 24-hour period.
  • Décor - Provide rock and décor for hiding places and plenty of room for movement



What to feed your cardinalfish

A well-balanced cardinalfish diet consists of:

  • Flakes, pellets, freeze-dried and frozen food
  • A varied diet will help to ensure proper nutritional balance


Things to remember when feeding your cardinalfish:

  • Depending on species and size, feed small amounts two to three times daily, no more than fish will eat in 1 to 2 minutes
  • Thaw frozen food before feeding


Cardinalfish care

  • Water care: Maintaining great water quality with regular water changes and adequate filtration is important to help keep your cardinals healthy
    • Daily: Check filter, water temperature and other equipment
    • Weekly: Test water quality at least once a week
    • Weekly to monthly: Change 10 to 25% of the total volume of water every two to four weeks, or as needed. Change filter media monthly
  • Avoid overcrowded conditions, as this is a major cause of stress and disease. Maintain good water quality with regular water changes and adequate filtration

Where to buy 

 In store and online: Cardinalfish are available for purchase at Petco online and in store; availability varies by location. If visiting your local location, call ahead to check availability.


Tank mates

  • May become aggressive in an overcrowded aquarium
  • Compatible with: 
    • Dwarf angelfish
    • Blennies
    • Butterflyfish 
    • Clownfish
    • Gobies
    • Dartfish 
    • Filefish 
    • Foxface/rabbitfish 
  • May be compatible with: 
    • Large angelfish
    • Damselfish
    • Psuedochromis
    • Tangs 
    • Wrasses


Signs of a healthy fish

  • Clear eyes
  • Healthy appetite 
  • Bright, even coloring
  • Fins completely intact and undamaged
  • Free of parasites or disease 

Red flags (If you notice any of these signs, contact your local aquatic specialist or veterinarian.)

  • Loss of color or appetite
  • Spots or fungus on body or mouth
  • Listlessness
  • Labored breathing 
  • Weight loss
  • Cloudy eyes
  • Erratic swimming
  • Frayed fins


Common health issues

Health Issue Symptoms or Causes Suggested Action
Health Issue Fin rot Symptoms or CausesFrayed or disintegrating fins; the base of the fins usually reddens. Suggested ActionImprove water quality; consult your local aquatic specialist or aquatic veterinarian for treatment.
Health IssueMarine ich Symptoms or CausesCysts on fins, gills and skin; rapid breathing, excess skin mucus or pale skin, Fish rubs against hard objects or swims erratically. Suggested ActionQuarantine fish immediately and use a commercial parasite remedy. Complete a water change, freshwater dips can help dislodge the parasites; consult your local aquatic specialist or aquatic veterinarian for treatment.
Health IssueBacterial infections Symptoms or CausesCloudy eyes, open sores and/or reddening of the skin. Suggested ActionImprove water quality; use a commercial antibacterial remedy as directed, consult your local aquatic specialist or aquatic veterinarian for treatment
Health IssueViral infection (lymphocystis) Symptoms or CausesWhite nodule growths on fins or body Suggested ActionImprove water quality; consult your local aquatic specialist or aquatic veterinarian for treatment


  • Where can I buy cardinalfish? Various cardinal species are offered in our Petco Pet Care Centers as well as offered on 
  • How do you care for a cardinalfish? Specific care requirements will vary by species, but all cardinalfish should be housed in a fully cycled marine aquarium and be provided daily feedings of a carnivorous diet 
  • What types of cardinalfish are there? Cardinalfish are members of the Apogonidae family, which consists of approximately 370 species
  • What size do cardinalfish get? Cardinalfish adult size will vary by species, but they range from as small as 1 inch to as large as 9.5 inches, with most of them staying smaller than 4 inches. 
  • What tank size should I get for cardinalfish? The aquarium size will depend on the species selected, but the larger the aquarium the less chance of water parameter changes happening quickly. For a single small-sized cardinal, a properly set up 5-gallon marine aquarium is the absolute minimum.

Additional care sheets

Notes and resources

Ask a Pet Care Center associate about Petco's selection of products available for the care and happiness of your new pet. All products carry a 100% money-back guarantee.

Because all aquatic life are potential carriers of infectious diseases such as atypical mycobacterium and salmonella, always wash your hands before and after handling your aquatic life or habitat contents to help prevent the potential spread of disease.

Pregnant women, children under the age of 5, senior citizens and people with weakened immune systems should contact their physician before purchasing or caring for aquatic life and should consider not having aquatic life as a pet.

Go to for more information about aquatic life and disease.



The information on this Care Sheet is not a substitute for veterinary care. If you need additional information, contact your veterinarian as appropriate.