Are your fish showing danger signs?

Are your fish showing danger signs?

When you pet an animal, it is essential to have complete know-how about it. There are plenty of benefits of knowing inside out about your pet. Right from what they like to eat to what their natural behaviour is- help to detect a lot of health issues and other problems at an early stage. And the earliest you know about your pet, the better cure you can provide to them for any health problem.

Most of the time, what seems a natural or normal part of the fish’s behaviour provides some hints about its health. Observing every fish for some time after every few days can probably provide distinguishing and alarming symptoms in some cases. Reading the books to know about fish behaviour is good but practical knowledge makes you professional.

Generally, when a disease is detected in its early stage, it becomes easier to cure rather than when it gets severe. Therefore, in this article, we will understand a few danger signs or symptoms that fish show in the early stages of many diseases. Understanding them will help an aquarist detect the health problem of the fish at an early stage.

Abnormal Swimming

When the fish are healthy, they swim throughout the tank happily. Their movements can easily show that they are happy inside their ecosystem. However, if you find the fish moving in circles or just drifting with the currents and not making any efforts to swim, the chances are it is under some health problem.

Likewise, the fish may seem drunk, sinking at the bottom and not being able to raise itself. Sometimes, the fish swim only at the surface and are unable to swim any further down. All these situations come under abnormal swimming. When there is some severe health issue, you will notice that the fish is swimming upside down, and its belly is pointing towards the surface. It is when you need to check on the health of the fish and provide the best treatment possible.

Respiration and Gills

Fish breathe through their lungs. It is essential that the gills of the fish are healthy. If you notice that your fish is gasping for air and moving abruptly to breathe, consider it as a warning sign. There could be plenty of reasons for this-

  • Improper aquarium maintenance– If the fish is not able to get adequate oxygen, it will gasp for air and move abruptly inside the tank. Try to provide or improve aeration in the tank by working on its maintenance. You need to carry out a series of frequent water changes so that the problem can go away faster.
  • Respiratory disease– If the fish is not breathing well even after improving the water quality, it could be suffering from some respiratory disorder. Since every fish have a different respiratory rate, it is not possible to determine how fast a fish breathes. Therefore, you have to observe your fish when they are healthy and notice how they breathe. Here, you have to remember that some fish breathe directly from the air. For such species coming up to the surface to gasp air once in a while is pretty normal.
  • Discoloured gill sheets– Generally, the gill sheets of healthy fish are pink. If you notice that the gill sheets are getting discoloured or turning pale, it could be because of some serious gill problem. However, exceptions are always there; for instance, in the case of Betta splendens, the gill sheets are pigmented.


Anorexia is one of the symptoms that fish show when they are sick. Losing interest in food and not eating anything the entire day is a sign of disease. If you are well aware of the normal feeding habits of your fish and recently noticed some changes in it, get cautious.

Anorexia comes in different forms. While some fish eat lesser than their normal feed, some completely refrain from eating. Also, some fish like to eat only certain kinds of food. Some fish change their behaviour pattern by just taking the food in their mouth when fed and later spitting it out. All these are danger signs when you should get careful.

The different reasons that may cause anorexia include the following-

  • Constipation– If the fish gets constipated; you can see abnormal swelling on its abdomen. Mostly it happens in fish with laterally compressed bodies. They have little room for the intestine that often leads to constipation. Since in such species constipation could be fatal, improve the diet and include fibre-rich foods.
  • Improper living conditions– When the water quality or water parameters are not proper, fish don’t feel like eating as their ambience is not suitable to survive. Try to check the water parameters and make them appropriate. In most cases, simply increasing the water temperature makes everything okay.
  • Unsuitable diet– Sometimes, fish do not like to eat what you are feeding it all day. Try to change the diet and add different things rather than giving only one thing every time.
  • Mouth brooding species– If there are mouthbrooding species in your tank, they may show the signs of anorexia in the spawning season. Such species refrain from eating while brooding because they have a large collection of ripe eggs that blocks their intestine.

Although anorexia can happen due to plenty of reasons, give time to your fish and observe for a while. By that time, check the water parameters and change their diet. Most of the time, doing just these minor things makes the fish alright.

Body Shape and Contours

You can know and conclude a lot about your fish by seeing its body shape and contours. The following physical changes need immediate action-

  • Swelling in any part of the body
  • Clamped or torn fins
  • Changes in the body shape
  • Irregularity in gills

These are some minor changes that can provide huge information about fish health. However, out of these changes, swelling of the abdomen could also happen if the fish is egg-bearing or pregnant. Additionally, it could be a sign of constipation, bacterial infections, and internal parasites.


Loss of colour is one of the signs that indicate the fish’s health. Generally, when the fish is unwell, it starts losing its colour. The good thing about the colour sign is you can easily distinguish it visually. Loss of colour specifies different issues-

  • Skin problem
  • Internal disease
  • Low level of oxygen
  • Stressed or frightened fish

Therefore, if you notice that the fish is looking faded and less vibrant than the other days, the reason could be some illness. If the fish look frightened, you can make a few changes in the tank, like changing the lighting condition, providing enough hiding spots and checking for the bullies and fin nippers. Many times, when you dampen the light, the condition improves drastically.

Here, one must know that fish do not always discolour due to stress or illness. Sometimes it happens as a defence mechanism and for many other reasons. Some are listed below-

  • As a defence mechanism– When there is some dominant male in the aquarium, the submissive ones dampen their colour and clamp their fins to avoid fights, violence and injury.
  • Spawning– When certain species of fish undergo spawning, they may show loss of colour. It is because the fish gets exhausted after raising a batch of fry.

Therefore, you need to observe closely and for a certain period of time to understand the reason for the loss of colour in your fish.

Cysts, Sores, Blood Stains 

The presence of cysts, sores, spots, etc., often indicates skin problems. Also, if you notice patches of blood stains or ragged white and brown patches, it simply is a sign of skin issues. Skin problems majorly occur due to ich, velvet and fungus attacks. If you observe the fish is itchy, scratching itself or rubbing the body to the sides of the tank or rough surfaces, it could be suffering from some skin issues that require immediate treatment.

Final Words 

Fish are the soul of the tank. If you take the appropriate care of the water animal and maintain all the water parameters, the fish will flourish and live happily throughout. Therefore, before you think about having a fish tank, understanding their natural behaviour and having complete know-how on them is essential.

Keep track of these danger signs to detect any problem in the early stage. Provide the right treatment immediately to prevent getting the disease severity. Information on these signs and symptoms helps to make the fish happy all through life, and your tank is beautiful always.

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