How To Tell If A Fish Is Sick

By Max. D Gray. Updated: January 16, 2017
How To Tell If A Fish Is Sick

Fish are one of the most interesting pets and most species are relatively easy to look after, but they can and do fall ill - they can even catch a cold! However it can be difficult to notice if your fish is unwell, so you'll need to inspect it up close for any abnormalities.

If you think that fish is sick, try not to worry! Like other animals, they can be treated and can make a full recovery. Here at OneHowTo, we are going to explain some tell-tale signs that can tell you if your fish are unwell.

You may also be interested in: How do You Know if Your Fish Is Pregnant
Steps to follow:

Here are some common symptoms that indicate that your fish might be suffering from a disease:

  • Its fins are frayed with a broom-like appearance or their fins might open very little when it swims.
  • Their movements are uncoordinated and they collide with objects or aquarium walls.
  • Their torso or any other part of their body is inflamed.
  • They keep their fins close to their body and move very little.
  • Their eyes widen, becoming larger than usual.
  • The fish rubs against an object in the tank, e.g. the water filter, plants or toys.
  • A lack of appetite compared to usual.
  • White spots on fins, face or body, possibly caused by fungi or lack of hygiene in the fish tank.
  • It has white cottony fluff on any area of its body.
  • Gills are purple instead of the natural reddish or pink colour.
  • Its body is inclined to one side - left or right, or its body is tilted with its tail pointing downwards whilst its head points upwards.
How To Tell If A Fish Is Sick - Step 1

In addition, prolonged inactivity may indicate that your fish is unwell. If you notice that your fish stays on the bottom of the aquarium and only rises to the surface for air, or even if it remains in one corner of the tank, it may be suffering from an infection or illness because most fish typically swim around quite frequently.


If the fins are stuck to its body , it could be a sign that water quality is poor. To fix this, change 50% of the water daily until the oxygen level is normal.

If the fish has white spots the size of a grain of salt in some areas of the body or fins, it is likely to be caused by the Ich parasite, which should be treated immediately. Furthermore, cotton-like substances on its body may indicate the presence of fungi, the treatment for which involves Rid Fungus or Maracyn.

Finally, if it has necrosis, its fins will look gnawed. This disease must be cured immediately to prevent it from spreading throughout its body. To do this, get some clean, warm water, add a few drops of garlic juice and any Stress Coat product to replace the slime coat.


Believe it or not, fish can also get colds. If you notice that it is swollen, it is likely to have a cold; if this is the case, feed it just peas for a few days. Buy some frozen peas and let one thaw before cutting it up into tiny pieces and throwing it into the aquarium. You could also feed your fish live/freeze-dried or frozen sand hoppers.


In our article on how to properly care for fish we'll give you some top tips on keeping your pets happy and the picture of health. You can also read about how to properly clean a fish tank which will help prevent your fish from becoming sick when done correctly.

If you want to read similar articles to How To Tell If A Fish Is Sick, we recommend you visit our Pets category.

Write a comment

What did you think of this article?
1 comment
Ron Blecher
my gold fish are laying at the botton wont eat like there lazy just laying around. they have grew to be real big.
How To Tell If A Fish Is Sick
1 of 2
How To Tell If A Fish Is Sick

Back to top