Why Are My Fish Dying? Simple steps to avoid this!

One thing that every pet owner dreads is the moment they see their beloved pet pass away. And fish owners are no different. Sometimes, they might go to sleep in the evening to find their fish dead in the morning. But why is that happening so often, why are my fish dying?

One of the most common reasons for death in fish is stress. But this stress has a very broad pool of other factors that increase stress levels in a fish. In some cases, we cannot prevent death, as it’s a result of a serious disease. But quite often, these premature deaths are very much preventable. 

Stress levels increase when fish are not living in the conditions they prefer; it might be wrong water parameters, tank settings, a tank that is too small, aggressive tank mates, improper diet, or even excessive diet.

Bacterial and fungal infections are also common reasons for deaths, while various diseases often affect different fish species. These diseases are sometimes treatable, but unfortunately, not every time. 

In this article, we’ll take a look at some of the most common reasons why your fish are dying, and how you can prevent those deaths.

Most Common Reasons Why Fish Die

We know that stress plays a huge role in longevity, and not just for fish. Stress can impact any animal, including human beings. The difference is that some fish respond to stress better than other species, but mostly, too much stress is never good.

It can lead to serious diseases and death. So, minimizing that stress can massively increase the life span of a fish. Here are the most common reasons why fish die.

Read our list of common Tropical fish diseases to learn how to treat any illnesses your fish may have.

Improper Water Parameters

One of the primary reasons and stress factors for fish is the wrong water parameters. And that often comes from a lack of research and knowledge prior to buying a fish.

Almost every fish needs different water parameters, whether it is the temperatures, the PH levels, water softness, and other factors. 

By using a test kit like API Complete Freshwater test kit you can monitor your water parameters to ensure perfect conditions.

This also includes sudden and severe temperature changes. This can, for example, happen when you’re buying a new fish. Make sure your tank for the new fish is already prepared with the right water parameters. Spend some time for research, ask at the pet shop about the water parameters. 

If you’re buying a tropical fish, for example, it won’t respond well if you put it into a tank where the water is too cold and not heated up yet. Temperature shock is a real problem and a possible reason for death.

Also, be mindful of the PH levels. While most fish will prefer neutral PH, that’s not always the case. Always make sure what parameters your new fish prefer, and try to stick to them on a daily basis.

A suitable Ph level for a community tropical aquarium is 6.8.-7.5 and a water temperature of 68-78 degrees.

You can purchase a pH test kit from your local pet store or online from stores like Chewy.com. Here is a link to the one we use. 

why are my fish dying
Regular tests and water changes will prevent fish from dying.

Incorrect Aquarium Setup

This reason ties up nicely with the previous one. From the get-go, the fish might be exposed to an environment they are not used to at all. One of the biggest mistakes is putting a saltwater fish and freshwater fish for that matter into unestablished aquariums.

It can take weeks to get the water parameters in a saltwater aquarium right before it’s mature enough and gone through the water cycle to be suitable to add fish.

With freshwater this water cycle is far quicker and can only take a couple of weeks.

If the water conditions in a new aquarium are not suitable it will only take a few days for your fish to get seriously ill and die.

The same goes for water temperatures. We’ve covered some of this in the previous section. But this is more important than some beginners think. Some beginners think that they’ll get away with “just putting the fish into the tank” and hope for the best. They couldn’t be more wrong! 

Choosing the best aquarium heater and the best aquarium thermometer to monitor the temperature is vital. Read our guides on both to help you make the right purchase. Links have been provided to our buyers guides.

Another thing that’s easy to miss is using chlorinated tap water for the new fish tank. That’s a common mistake; most fish don’t deal with excess chlorine too well, especially with tap water chlorine.

When the water goes through a water treatment plant, chlorine is added, as well as some other heavy metals. And these can be harmful to the fish.

Make sure that the water is dechlorinated and conditioned for the fish tank. We use API dechlorinate for tap water as we find it inexpensive and fast working.

The Aquarium is Too Small

Cramping together three Goldfish fish into a 10-gallon fish tank is a recipe for disaster. That’s just one example, but every fish needs ample space to live and survive.

Even if you’re looking to keep some small guppies together, they’ll still need enough space. And that’s especially the case if you’re looking to keep several of those fish together.

two nano aquarium
Nano or Small aquariums look amazing but are very difficult to keep

Not only will these fish become stressed, which can cause illnesses and health problems. What’s even a worse problem is that sometimes, these fish will turn aggressive and territorial with each other.

And that alone can cause injuries, as they will start to fight. In more severe cases, it might even cause death.

Again, the importance of research is crucial. Make sure you know how much space your fish need, and buy a tank that’s big enough to accommodate your fish. Sometimes, buying a larger tank is not a bad idea.

The Water is Too Dirty/Not Cycled

Regular water maintenance is key to ensuring that the water is clean enough for the fish. Additionally, you should always consider getting a good water filter. Filtering the water before you put the fish into the tank can massively increase the chances of having a good transition to your chance.

In most cases, it’s better to buy a powerful filter to keep up with the cleaning demands. Some fish can be messy, while saltwater tanks require a lot of equipment to keep the aquarium clean and safe for fish and corals. 

If you don’t clean your water, poisonous chemicals will start to build up, such as ammonia and nitrites. These can seriously harm your fish, and they might die if there’s too much of it. Especially in saltwater aquariums the effect of poor water quality can be fast and deadly.

I have seen whole aquariums wiped out within hours containing thousands of dollars worth of corals and fish. Several years worth of work gone due to harmful chemicals building up and going unnoticed. 

fish tank water changes
25% partial water changes should be carried out every 14 days

Make sure you perform partial water changes often enough – this can be once a week, or once every two weeks depending on the type of fish size of aquarium. Also, have a filter that’s powerful enough for your tank. It wouldn’t hurt to have a filter that can handle more than just the contents of your tank.

For larger aquariums above 36 Inches or 100 Gallons we recommend the Fluval FX4. This filter can handle any aquarium from 50-150 Gallons. Any bigger and we would recommend stepping up to its big brother the Fluval FX6 which is the crown Jewels in aquarium filters.

Incompatible Tank Mates

Always avoid keeping aggressive, larger fish together with smaller fish. While the smaller fish will mostly be able to get away, the larger fish might actively prey on them, or harm them.

As a result, the smaller fish will get stressed and will start to hide. At least make sure that you give them some hiding spots.

Ideally, though, you’ll want to avoid these kinds of situations. Another thing that can be bad for your fish is having two aggressive male fish together.

For example, two male betta fish in the same tank can cause havoc. They’ll fight each other constantly, causing injuries or in severe cases, deaths. A lot of other fish males will do that, so make sure you know what you’re getting.

Overfeeding the Fish

As we already said, fish deaths are often preventable. And some owners will overfeed their fish to a point where they get sick and die. This can cause digestive problems and additional water pollution. The first will kill the fish directly, while the second one, if not treated, indirectly. 

Overfeeding will also lead to obesity in fish. That will massively decrease their quality of life. Always keep track of how much you’re feeding your fish; some fish only need feeding once a day, or even less often than that.

over feeding fish
Never overfeed your fish

Old Age

If your fish reaches old age, congratulations, you’ve done a good job of keeping your fish happy and healthy for a long time. But unfortunately, there comes a time when we simply have to say goodbye.

There is no escaping that the fact your fish will die one day. Some fish last up to a few years, while others can live up to 10 years or even more. It mostly depends on genetics, too.

Diseases, Infections, Parasites

Diseases can be caused directly by the excess stress the fish endure. That’s why you should always aim to keep stress levels as low as possible. But, sometimes there’s just nothing we can do with diseases.

Some are curable, while with others, there’s a very slim chance of recovery. But as long as there is a chance, you should try everything you can.

Bacterial and fungal infections are also common, and they are sometimes caused by poor water quality. The same goes for parasites.

These can also enter the water through live foods like bloodworms which should always be washed in clean water before feeding to your fish or when you introduce new plants that might have these parasites on them. Make sure your food is vetted and the plants scrubbed clean.

Fish Are of Poor Health When You Buy Them

Some fish will die shortly after you buy them for no particular reason. It turns out that the fish you bought was already sick before you bought them. Unfortunately, it was too late.

Next time you buy a fish, make sure you buy from a respectable seller. Also, inspect the fish for any signs of diseases and infections.

Always make sure your new fish are healthy when you purchase them

Conclusion: Tips to Avoid Premature Fish Death

Once you have checked all the safey precautions mentioned above you can start to add a routine and schedule to your fish keeping hobby. This will ensure you never miss anything that could harm your fish.

Once you get into a daily, weekly and monthly routine you’ll ensure that your tropical or saltwater fish have all the very be care you can give them.

Daily Tasks involve:

  • Feeding your fish 2-3 times a day, small amounts
  • Checking for any signs of diseases
  • Keeping the lights on for 10-12 hours a day to ensure your plants survive
  • Checking the Temperature
  • Remove any uneaten foods

Weekly Tasks

  • Removing any dead leaves and excess debris
  • Partial water change depending on the type of fish and size of aquarium 25% is good
  • Feed your plants or corals with a liquid fertilizer or other suitable feeds
  • Clean the glass inside and out
  • Check the water parameters like pH, Nitrates and other parameters

Monthly Tasks

  • Clean and check your filter. Always rinse the filter material in water from your aquarium. Take a jug of water out and rinse and wash the filter material in that. Never under the tap or boiling water.
  • Gravel clean your aquarium to prevent build u of harmful chemicals
  • Another water change 25%
  • Full water parameter check, Temperature, Ph, Nitrates, etc

Here are some tips to help you ensure your fish will live longer. This is a quick summary of all the solutions we have talked about that will ensure your fish don’t die and live a long and happy life.

  • Measure your water parameters and adhere to the recommendations when it comes to temperature, PH levels, softness.
  • Make sure you prepare the tank before you insert the fish.
  • Buy a powerful filter like the Fluval FX4
  • Make regular water changes and cycle before adding fish
  • Make sure your tank is big enough to accommodate your fish.
  • Clean the tank often 
  • Make sure you have only the fish that will go together well.
  • Only feed your fish when they’re hungry 2-3 times a day & small amounts
  • Minimize the stress
  • Ensure the fish you buy are healthy to start with.