What To Do If a Fish Dies In The Tank?

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A fish died in your aquarium: what should you do now?

I bought my first aquarium a few years ago and unfortunately some fish have died since then. This happens, but it is important that you know what to do.

 

It is important that you remove a dead fish from the aquarium as soon as possible to protect the other fish. A fish may die from disease or toxic water parameters, and it is important that you find and correct the cause. Measure water values and use medication if necessary.

 

If you have other fish in your aquarium, make sure they don’t get sick and die too. I will tell you what the most common causes are and how you can counteract them. It’s also helpful to know step by step if your aquarium is still safe. So read on.

 

The first thing you do when a fish dies

If you suddenly see a dead fish in your aquarium, you should remove it as soon as possible. In warm water, a dead fish can quickly rot and become a great danger to all the other fish.

 

Use a landing net so you don’t have to touch the fish. It is best not to flush a dead fish down the toilet, it is best to throw it directly into the garbage. If you can’t throw it out immediately, put a bag around it.

 

Now that we’ve got it all figured out, you need to go and check for other dead fish. And of course, you want to know what caused your fish to die, because if it’s a disease, you need to do something about it.

 

Common Causes of Aquarium Fish Death

There are countless reasons why an aquarium fish may die, so you will need to determine what is happening to you. Here is a list of common options. We’ll take a closer look at different diseases and how to resolve them.

 

Natural death from old age. A small aquarium fish lives on average 5 years, but of course this also depends on the type of fish. Although natural death is the most common, you should always look for another cause, as your aquarium must remain safe.

 

Ammonia is a deadly waste product for fish. It is found in fish poop and breaks down into nitrite and nitrate in a healthy aquarium. If your aquarium is brand new (less than 2 months old) or if you have a lot of decaying plant remains, this is probably the cause.

 

Fighting between fish can certainly be deadly. Your fish will not suddenly die from it, but if a fish is chased for a long period of time, the fish can die from too much stress.

 

White spot is a very common disease in both fresh and salt water. We’ll talk about it later, but you can recognize this disease by white spots all over your fish.

 

The water is too warm and your fish will die. This is especially a problem in the summer when it is very hot outside. It is then difficult to keep the temperature “down”. If your heater is broken, the water may also be very hot.

 

Old tank syndrome is an easily preventable condition.

 

Many of these causes are due to dangerous water parameters. It is therefore important that you measure your water with a “test kit”. If you don’t have a way to test your water yet, I can really recommend this test kit from JBL. It is much more accurate than paper test strips and therefore gives a better picture.

 

What are the “healthy” values of water

Before you start looking for a solution to common illnesses, it is extremely important that you know exactly what the good and bad water parameters are. Not all water values are equally important, so what should you pay attention to.

 

The most important value is the amount of dissolved ammonia, because ammonia in very small amounts is already deadly for fish.

 

If a fish is dead, always measure the ammonia concentration first

 

The amount of ammonia should not be measurable and should be as close to 0 ppm (parts per million) as possible. This also applies to nitrite.

 

Nitrate may be measurable, but must remain below 50 ppm in order not to become toxic to fish.

If a fish has just died, the other water parameters do not matter. Just ask yourself if the water values have been consistent over the past 48 hours. If values such as pH, temperature or hardness fluctuate a lot, a fish may feel stress.

 

 

Your aquarium is too new and not yet ready for fish

An aquarium must “run” without fish for about 2 months to develop enough bacteria to keep your aquarium safe. If you put fish in a new aquarium immediately, they will die.

 

During the first few weeks, a bacterial colony will develop in your aquarium filter. These bacteria can break down ammonia into nitrite and nitrate, so they are essential for keeping your aquarium safe.

 

If you didn’t know or are very impatient, your fish may be producing ammonia that cannot yet be broken down by the aquarium. Ammonia is already deadly in low concentrations and can kill your fish.

 

It is important to still give your aquarium time to break in properly. If you don’t have time for this, be sure to use part of a “live” filter from another aquarium. The filter from a long-running aquarium already contains bacteria, so you can start an aquarium quickly!

 

Whitehead: Recognizing and healing

Look carefully for small white dots on the deceased fish or on other fish in your aquarium. The image below is a good example of whiteheads, they are really just very small dots!

 

If your aquarium is suffering from white spot, the first thing you need to know is that not only the fish with spots are infected. The white spot lives in the water of your aquarium: your whole aquarium is sick!

 

So, simply removing the fish with a spot from the aquarium makes no sense. You need to use medicine that cures the whole aquarium. Go to a pet store or aquarium store as soon as possible and buy medicine that works against the “Ich” or (white) spot.

 

The packaging will tell you the best way to avoid white spots. This is often a multi-day course of treatment and they recommend raising the temperature of your aquarium to speed up the process.

 

For more information on white spot I can refer you to a page on the site “aquariumfans”, they have more information here .

 

Old tank syndrome: recognizing and curing

 

If you’ve just added new fish to your aquarium and they die within a day, you’re suffering from old tank syndrome.

 

Ammonia is toxic in small amounts, but quickly converts to nitrate in a healthy aquarium. Nitrate is much less toxic, but can still be stressful at high concentrations. It is therefore important that the nitrate concentration does not rise too high. If it does, you are suffering from “old tank syndrome”.

 

The nitrate concentration in your aquarium will rise if you don’t do enough maintenance. Every time you replace some of the water in your aquarium with clean water, you remove nitrate from the water. Aquarium plants can also help you remove nitrates from the water.

 

I know better than anyone that it is sometimes very tempting to just fill the aquarium and not take water from the tank first. If you do this too often, you will not remove the nitrate from the water and it will slowly increase.

 

Old tank syndrome is not dangerous for old fish, only for new ones

 

Fish that are already in your aquarium will slowly get used to higher nitrate levels. Because of the gradual build-up, they learn to live with it and they don’t die.

 

The fish you just bought are not used to the high concentration of nitrate and will be in for a real shock when they are released into your aquarium. They will look very stressed and die within two days.

 

If you suffer from OTS, change the water by 10% every day, so that the nitrate concentration will slowly decrease.

 

Frequently asked questions

 

Do I need to change water if a fish dies?

A 50–60% water change should be conducted every 5–6 weeks to prevent any type of nitrate accumulations. If a fish dies or there is an outbreak of some disease, go for a 10% water change

 

 

How long can a dead fish stay in tank?

Not necessarily if the dead fish is in the tank for a short period of time say 2 to 3 hours. But if it is in it for a long period of time then you should consider changing atleast 50% of the water. Remember never change 100% water since the beneficial bacteria in the water may die off.

 

do i have to clean the tank after a fish dies

Dead fish can cause a lot of problems in a fish tank, from polluting the water to attracting unwanted pests. Therefore, you need to act quickly to remove the dead fish and properly clean and sterilize your tank to prevent the spread of potential disease.

 

Will a dead fish contaminate a tank?

Remove. Any dead fish should be removed, as its body will quickly rot in the warm, bacteria-laden water. A corpse will pollute water, risking the health of other fish in the tank. If it died from disease the last thing you want is other fish consuming its body parts, so remove immediately.

 

Ben
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