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Rainbow Fish

includes rainbow fish species

Rainbows are a group of freshwater fish originating in Australia and Southeast Asia. This long-established favorite is tolerant of most foods and conditions. These peaceful, schooling fish dwell in the middle or upper levels of the aquarium.

Rainbow Fish

Rainbow Fish Facts

Average Adult Size 1 to 6+ inches long, depending on species
Average Life Span depends on species
Diet omnivore
Minimum Aquarium Size 20+ gallons, depending on species
Water Temperature: 72-82°F


A well-balanced Rainbow Fish diet consists of:

  • Flaked, pellet, frozen or live food.
  • Avoid exclusive food which is not nutritionally complete.


Things to remember when feeding your Rainbow Fish:

  • Depending on species and size, feed small amounts 2-3 times daily, no more than fish can eat in 3-5 minutes.
  • Thaw frozen food before feeding.


  • Keep in an appropriate size aquarium; provide plants, rocks, caves and decor for hiding places and plenty of room for movement.
  • Stable water quality, water temperature, and pH levels are critical to the health of aquatic life. If you are unsure of your water quality or pH levels, Petco provides free water testing.


  • Males and mature fish are generally more intensely colored.
  • Juveniles of both sexes are often very different in coloring from adults and can appear like separate species.
  • Rainbows are very active and require plenty of space.

Habitat Maintenance

  • Daily: check filter, water temperature and other equipment.
  • Weekly: check water quality at least once a week.
  • Monthly: change 10-25% of the total volume of water every 2-4 weeks, or as needed.
  • Introduce new inhabitants to the aquarium gradually.


  • Check Petco's freshwater compatibility care sheet for species specific information.


Signs of a Healthy Fish

  • Clear eyes
  • Eats vigorously
  • Hides most of the time
  • Fins completely intact and undamaged

Avoid overcrowded conditions; they are a major cause of stress and disease. Maintain good water quality with regular water changes and adequate filtration.

Red Flags

  • loss of color
  • spots or fungus on body or mouth
  • listlessness
  • erratic breathing

Common Health Issues

Health Issue Symptoms or Causes Suggested Action
Health Issue Fin rot Symptoms or Causes Frayed or disintegrating fins; the base of the fins usually reddens. Suggested Action Improve water quality; consult your veterinarian for treatment.
Health Issue Ich Symptoms or Causes White spots appear on fins and body; fish rubs against hard objects or swims awkwardly. Suggested Action Quarantine fish immediately; use a commercial ich remedy for at least two weeks..


Ask an associate about Petco's selection of books on Rainbow Fish and the variety of Petco Brand products available for the care and happiness of your new pet. All Petco Brand products carry a 100% money-back guarantee.

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

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

Go to the Centers for Disease Control at for more information about aquatic life and disease.

This care sheet can cover the needs of other species.

Note: The information on this Care Sheet is not a substitute for veterinary care. If you need additional information, please refer to the sources on the following page or contact your veterinarian as appropriate.

Developed with and approved by a qualified veterinarian.