How to Save a Dying Fish Scientific Way

Carol M.
Fisheries Consultant

Fish are the best pets to keep, especially in an urban setup. These creatures are peaceful and make no noise. Again, they require less space to keep and minimal care.

However, like any other living creature, their health can get compromised. It would be best to learn how to identify symptoms of a seriously ill fish or dying one and know how to save them. Some of the symptoms include;

  • Cloudy eyes
  • Swollen belly
  • Lack of appetite
  • Gasping for air at the water surface
  • Rapid breathing
  • Discoloration on the gills or the body
  • Swimming erratically
  • Clamped fins

If your fish presents some of the symptoms above, it's time to save it through the following ways.

Some Steps to Save your Dying Fish in Scientific Way

  1. Quarantine Fish

The best action you should take is to separate the fish from other stock in the tank. Some of the infections are contagious. Quarantining prevents contamination of the water and infecting healthy fish.

Transfer the sick fish to another tank with filtered water. It's better if the water is cooler for the fish to breathe well. Avoid using tap water as it may contain some contaminants. Remember to acclimate your fish to the new tank to avoid shock.

  1. Change Water

After transferring the sick fish, it's best to change the water several times. Avoid adding any additives. Keep observing the fish for several hours; it may respond and improve the symptoms. Be keen as you change the water to avoid interfering with the hardness. A sick fish can’t tolerate hard water, which may affect it more.

As a rule, don’t replace more than 15% of the water because you may shock your fish.

  1. Check on Water Quality

Poor water quality is a major cause of fish illness and infections. These creatures require favorable water quality parameters like Ph, temperature, salinity, ammonia, nitrate, hardness, and alkalinity.

If some of the parameters are too high, your fish may die even with a water change. Ammonia, nitrate, or nitrite being too high requires immediate attention. Use a liquid-based kit to test these parameters. If parameters are out of range, like pH and temperatures, don't make drastic adjustments. Make small changes over several days to ensure your fish survives.

Best water parameters for your fish, especially the tropical include:

Parameter Range
AmmoniaLess than 0.1 mg/l
Nitrite0 mg/l
NitrateLess than 20 mg/l
HardnessGreater than 100 mg/l
Temperature78-82 F


  1. Medicate Your Fish

If your fish fails to improve after a water change, you need to treat it. Check for any signs of diseases like cloudy eyes, slime on the body, and fin rot. Use a fungus eliminator which is an anti-protozoan or antibacterial treatment.

Be careful when using these commercial medications, as they may cause more harm to the fish. You should be sure of the diseases or the parasites you are treating. But, in case you aren't sure, consult a veterinarian officer on the same.

  1. Check the Food Quality

A sick or dying fish may be eating poor quality food. The food may lack vitamins causing a weak immune system. If you use your food for more than a year, it may lose nutrients. Use your feed within six months of opening and discard the remains.

Again, ensure you store it properly. Always keep the food in a sealed container in a cool environment. Ensure you also feed your fish with the amount they can consume in a few seconds. If they are suffering from swim bladder issues, provide them with fish veggies like frozen peas; they have high fiber content and low protein.

Causes of Death in A Fish

  • Acute stress

Fish get stressed from many issues like illness, poor water conditions, parasites, injuries from being bullied, and more. You will notice a stressed fish if it hides excessively, has much weight loss, or is ill.

  • Incorrect Tank Size

Follow the 1-inch of fish per gallon of water. Again, ensure you provide the appropriate requirements of your fish and stock appropriately. If you mess with the stocking and the size of the tank, you will lose your fish.

  • Incompatible Tankmates

Some fish are territorial and will chase other fish in their area. Others are very aggressive and keep bullying. So, it’s best to research the compatible fish; otherwise, the peaceful species will suffer from injuries and stress.

  • Poor Water Quality Parameters

Keeping your fish in a healthy environment prevents premature death. If compounds like ammonia, nitrite, or nitrate go beyond the acceptable levels, they poison your fish leading to death. Again, if temperatures and pH aren't favorable, they make your fish inactive and cause shock. Sick and young fish are more at risk and can't stand the situation.

  • Poor Tank Management Practices

An aquarium requires various management practices to keep it clean and provide a healthy fish environment. Some of these practices should be done every month as follows;

  • Water changes- replacing old water with fresh one dilute waste compounds and helps beneficial bacteria. However, you shouldn't remove too much, making the bacteria die off and causing subsequent problems. Don’t change more than 15% of the water.
  • Vacuum gravel- helps remove the remaining food particles and debris trapped in the gravel. You need to clean a little using the best gravel cleaner since most microbes live here.
  • Filter maintenance- always clean the dirt in the filter once a month. Avoid dumping the sponges unless they are worn out. Remember, these sponges are home to beneficial bacteria and replace activated carbon once a month.
  • Testing water – it’s best to keep testing your water even when everything seems fine.


A fish can die due to several factors, either natural or artificial. Some of the reasons include old age, diseases, water pollution, parasites, etc. As a fish keeper, always observe your fish for any abnormal behaviors or symptoms. If you notice any dying symptoms, it's best you try saving your fish with the techniques above. However, the best remedy is to prevent factors leading to fish death as much as possible.

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