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Large Marine Fish

Large Marine Fish

includes large angels, tangs, groupers, large wrasse and triggers

Angelfish are identified by the distinctive spine on their gill cover. Tangs are often called surgeonfish because of the scalpel-like spine at the base of their tail. Triggers are known to exhibit a level of intelligence that is unusual compared to other aquatic life. Wrasses have a greater variety of shapes, sizes, colors and habitats than do most other fish groups.

Large Marine Fish

Large Marine Fish Facts

Average Adult Size 6 to 24+ inches long, depending on species
Average Life Span depends on species
Diet omnivore
Minimum Aquarium Size 50+ gallons, depending on species
Water Temperature: 72-78°F, depending on species, as some prefer temperatures outside these parameters
Salinity Level: 1.020-1.025


A well-balanced Large Marine Fish diet consists of:

  • Flakes, pellets and frozen food.
  • Algae sheets should always be present for angelfish and tangs.
  • Vary diet to ensure proper nutritional balance.


Things to remember when feeding your Large Marine Fish:

  • Feed 1 to 2 times daily; some species need 2 to 3 feedings per day.
  • Thaw frozen food before feeding.


  • Keep in an appropriate size aquarium; provide rock and décor for hiding places and plenty of room for movement.
  • Live rock can provide a natural food source while also enhancing biological filtration.
  • Stable water quality, water temperature, and pH levels are critical to the health of the aquatic life. If you are unsure of your water quality or pH levels, Petco provides free water testing.

Normal Behavior

  • Angelfish can be territorial; tend to inhabit the middle and lower levels of the aquarium.
  • Some tangs are solitary and territorial, may be aggressive to new aquarium inhabitants.
  • Some tangs, such as yellow tangs, may be kept in schools of 3 or more in odd numbers
  • Some triggerfish may be aggressive towards each other and other tank mates.
  • Many wrasses like to bury themselves in the substrate at the bottom of the tank at night.

Habitat Maintenance

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


  • Check Petco's Marine Compatibility Care Sheet detailed information for each large marine fish species.


Signs of a Healthy Fish

  • Clear eyes
  • Healthy appetite
  • Bright, even coloring
  • 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
  • erratic swimming
  • labored breathing
  • cloudy eyes
  • weight loss

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 aquatic veterinarian for treatment.
Health Issue Marine ich Symptoms or Causes Cysts on fins, gills, and skin; labored breathing, excess skin mucus or pale skin. Suggested Action Treat entire aquarium with a commercial parasite remedy and improve water quality; freshwater dips can dislodge the parasites.


Ask a store partner about Petco’s selection of books on large marine fish and the variety of private brand products available for the care and happiness of your new pet. All private brand 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 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.