Got a sick fish?

Fish with disease can show a variety of signs. If you notice your pet fish having any unusual disease signs, contact your veterinarian for further advice. These are some of the most common signs of disease seen in pet fish:

  • Appearing disoriented, such as swimming upside down
  • Leaving food uneaten
  • White spots on fins or body
  • Discolored gills
  • Trouble breathing such as gasping at surface of water
  • Bulging eyes (one or both)
  • Mucus accumulation on the body
  • Rubbing on hard surfaces
  • Unusual isolation from the group of fish (if housed with others)
  • Skin lesions/sores anywhere on body
  • Bloating
  • Crooked back or other changes in fish shape or size
Many of the following signs found above are commonly associated with a variety of diseases found in fish. Below are some common diseases found in pet fish:
  • Physical injury
  • Parasites such as white spot disease or “Ick”, nematodes, anchor worms, fish lice, gill maggots, monogenean flukes
  • Bacterial infections such as columnaris disease and mycobacterial infections
  • Fungal infections such as Saprolegnia, Branchiomyces, and Fusarium.
  • Finrot or ulcer disease: rotting of the fins caused by bacterial or fungal infections
  • Hole-in-the-head: holes in the front or side of a fish’s head. The cause for this disease is still unknown but several factors are believed to play a role
  • Fish pox: caused by a fish herpes virus resulting in gray, pink or white wart-like growths (common in Koi fish)
  • Velvet or coral fish disease: a parasitic disease that  results in dusty and slimy scales (common in tropical fish)
  • Ammonia or chlorine poisoning resulting from poor water quality

The AVMA would like to thank Raphael A. Malbrue, Tuskegee University College of Veterinary Medicine Class of 2014, for generating this document during his July 2012 externship at AVMA headquarters.