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How to recognize distress in your fish

Obviously, fish don’t have the ability to speak to us when something is stressing them out. In order to recognize if something is wrong with one of your fish, you have to observe their behavior. When your fish doesn’t follow its normal routine, it may be a sign of distress.

Fish are great actors, they will hide their illness and act as normal as possible, this is usually because they don’t want predators to spot them being sick and choosing to rather eat them because they will die anyway. This toughens aquarists’ jobs because we will have to be extra observant in order to spot distress.


But how do you know if your fish are distressed or not? You can look out for the following symptoms:

  • they lose their appetite,
  • they become more aware of their surroundings,
  • are they breathing faster or slower,
  • are they energetic swimmers or are they slow-moving
  • and last but not least, did their colour change.

Loss of appetite can become a serious problem, because as all normal creatures need food as a source of energy, when a fish doesn’t eat, they don’t have enough energy to reproduce or heal themselves when they are ill. It might also cause the fish to become weak and they will easily catch diseases. Fish are supposed to eat every time that you put food into the water. If it eats every time, it is healthy.

When a fish is normally an active swimmer and now it tends to constantly stay in one place, it is also a sign of distress, it might also be a symptom of distress when a fish is usually lazy but suddenly swims actively.

You can spot the difference in the fish’s breathing by looking at how many times their gill covers move. If they move less often than normal, or more often than normal, it is a sign of distress and you should observe the fish more so that you can distinguish what is wrong with it. A normal respiration rate for fish is about 20-80 gill movements per minute, anything below or over that rate can be a sign that something needs to be changed in your tank.

Parameters and systems in aquariums always change and because of that, distress in tanks cannot always be prevented. Distress isn’t necessarily always a bad thing. Distress helps fish to adapt to their environment more easily. Distress is only a bad thing when it may cause the fish to die.

Water quality is the main thing that stress fish out. When fish are stressed out they breathe faster and that may lead to a build-up of mucus in the tank that might become toxic to other fish.

Competition between species can also cause distress in tanks. It is recommended that tanks are populated with fish that easily get along with each other. When fish are bullied by other fish, they isolate themselves and might not get enough food to eat and that will lead to disease or even death.

It is important to watch your fish closely so that you know their normal behaviour and can spot when one of them aren’t behaving as they should. For any inquiries about abnormal fish behaviour please feel free to contract us at:

Tel: 011 100 4678

Email: sales@easyreef.co.za