spotting illness in fish
Are your fish healthy?


Like all living creatures, fish can fall ill. And, just like the rest of us, if it’s caught on time it can be the difference between a long, drawn-out illness or even life and death. That’s why it’s important to take a moment to observe the behavior of your fish during feedings. If you’re unsure as to what you’re looking for when it comes to spotting sickness in aquatic pets, then you definitely want to read on to learn more about the signs and symptoms your fish may present when they’re feeling under the weather.


If you observe a white or gray growth on the surface of the skin resembling cotton, you’re most likely looking at fungus.

Anchor Worms

Rubbing or scratching against objects in the tank and/or the appearance of greenish-white threads on the skin accompanied by inflammation are signs of anchor worms.

Clamped Fin

If your fish are acting listless and their fins are folded or clamped tightly against their bodies then a condition called clamped fin is likely the culprit.


Yes, fish can get a type of lice, too. You can tell if they’ve got lice by the red spots they develop and the rubbing/scratching behavior similar to that seen in anchor worms.


Symptoms for this also include clamped fins, but you’ll notice gasping at the surface of the tank and sand-like grains on the skin that some people describe as looking like salt.

Body Flukes

This illness presents with multiple symptoms that include what appears to be a layer of mucus membrane, a reddish tint to the skin, scratching/rubbing against surfaces and gills that move rapidly.


A bacterial infection of the kidneys, symptoms of dropsy present as bloating and protruding scales.


detecting sickness in fish
Take a moment to observe your fish for potential illness periodically


While all of the above are common diseases owners of aquariums have to deal with in the course of caring for fish, if they exhibit any of the following signs it’s also recommended that you speak with a professional to assess your treatment options.

  • Skin lesions, sores or inflammation of the body
  • Bulging of the eyes, one or both
  • Discolored or inflamed gills
  • Avoiding other fish, especially if they’re schooling fish
  • White or gray spots or splotches on the body
  • Lethargy, disorientation, or swimming upside down
  • Trouble breathing/ gasping
  • Bloating
  • Rubbing against surfaces even without other attending symptoms
  • Lack of appetite
  • Changes in appearance (drooping fins, color, crooked back, etc.)

illness in fish
Keep your tank clean to reduce opportunity for illnesses



Seeking the opinion of a professional and beginning treatment at the first sign of illness is going to be the best bet for saving your pet. Don’t panic. It could be something as simple and inexpensive as adjusting the chemistry of your aquarium. Either way, you should be able to seek advice from your regular fish supplier or employees of pet stores that sell them. Just don’t wait too long.