why do angelfish die so easily?

Why Do My Angelfish Keep Dying?

It is distressing to discover that your beautiful angelfish have died during the night. It’s even worse if you can’t figure out why. When it comes to sudden angelfish death, the reasons are pretty broad. These tropical fish require a heated and filtered tank with regular maintenance. If you fail to meet their specific requirements, they’ll die easily.

Angelfish might die from poor tank conditions, water changes, stress, and disease. These factors might even cause your fish to die with no warning. In more specific terms, angelfish die from tanks that are improperly heated or lack a filter. If the water hardness is off, or no conditioner is used, that can be deadly. You may be introducing new fish too quickly, or pairing them with the wrong tank mates.

In some cases, fish are sick before they arrive in your tank. If they’re kept in a fishbowl or overfed, they’ll only get sicker. Even healthy fish will struggle in a tank without hiding places or too little space. All this leads to stress, chemical imbalances, and fighting.

Why Do Angelfish Die So Easily?

Angelfish won’t die easily. In the wild, there are hundreds of thousands of angelfish that thrive. However, certain breeds are becoming endangered because of changes in ocean temperatures and conditions.

For example, the Clarion angelfish in Cabo Pulmo has a population of 60,700, according to Endangered Species Research. Like its wild brethren, your angelfish may be dying off because of their water, its chemical balance, and the incorrect temperatures.

Aside from that, pet angelfish also have more deadly conditions to face. Owners may place them in tanks that are:

  • Too small
  • Overcrowded
  • Improperly filtered
  • Filled with creatures that stress angelfish or cause them to fight
  • Lacking the correct amount of oxygen

These factors can lead to your angelfish dying very easily.

Do Saltwater Angelfish Die Easily?

Angelfish come in saltwater and freshwater varieties. The most common type that people keep is freshwater. That’s because they have a reputation for being easier to keep. Supposedly, they die less often, are more durable, and are more receptive to water changes.

In theory, saltwater angelfish aren’t weaker or more delicate. Instead, freshwater angelfish are easier to keep because they don’t require such specific conditions. To make it simple, you can cultivate a healthy tank with:

  • Unsalted water
  • Mild conditioner
  • A few changes in temperature
  • A careful eye on the chemical balance

This is easy for the average fish owner to manage. On the flipside, saltwater angelfish require a far more intricate chemical balance. The conditions of their tanks must be precise, and are difficult to replicate at a glance. You can’t pour water into the tank from your sink and add table salt.

Because of this, inexperienced owners are more likely to get the water parameters incorrect. This can lead to saltwater fish dying easily under a beginner’s hands.

angelfish keep dying but water is fine

Why Do My Angelfish Suddenly Die?

Angelfish can appear to die suddenly. At times, this will be within hours, with no warnings at all. At other times, the cause of death is a growing problem that has gone unnoticed until the fish has passed.

It’s frustrating, but there are many potential reasons why angelfish die seemingly out of nowhere. As noted by researchers from Virginia Tech, fish can die from:

  • Old age
  • Starvation
  • Injury
  • Stress
  • Water pollution
  • Suffocation
  • Diseases
  • Parasites

How can you catch these problems before they get lethal? Here are ways your fish might die suddenly.

Angelfish Died Overnight

If your fish died within a single night, this may have two causes:

Introduced To The Tank Suddenly

All new fish must be given time to acclimate to a tank. Otherwise, they will die from shock. Once you get fish home from the pet store,

  • Do not remove the fish from the bags
  • Float these bags in the tank for 15-20 minutes. This allows the fish to gradually become accustomed to the tank’s temperature.
  • Add small amounts of the tank’s water to the bag. This allows the fish to acclimate to the tank’s hardness and acidity.
  • A strong difference between the bag and tank’s water may require a slower acclimation process. You may need up to 30-40 minutes.
  • Quarantine new fish in a separate tank for 2 weeks. This allows the fish to acclimate in peace. It also prevents any previously unknown diseases or parasites from getting into the main tank.

Water Imbalance

A chemical imbalance is the primary reason for angelfish to die overnight. If new fish are introduced to this, it’s a sudden shock to their system. They won’t recover from it. They will show no immediate signs, but die within a few hours. If your fish is hardy, it may even take all night.

Tanks that aren’t set to the right parameters can also be a catalyst for a secondary problem. Let’s make sure your tank is correct, so you don’t kill your fish suddenly.

Tank Size20 gallon + 15 gallons for each additional fish
Temperature Range78° F – 84° F
pH Range6.8 – 7.8
Hardness54 – 145 ppm

Aside from that, you should consider:

  • Is the filter’s output gentle enough that the fish aren’t exhausting themselves?
  • Is all the equipment functioning properly?
  • Has the temperature changed suddenly?
  • Have I added new water without letting it adjust?

All My Angelfish Keep Dying

Disease, fungal infections, and parasites can appear seemingly out of nowhere. While most show clear symptoms in your fish, others may go unnoticed. They’ll rapidly get out of control without your intervention, and infect all new fish.

Closely inspect any ailing or dead fish. Are there any abnormal growths? These may include:

Angelfish in particular are vulnerable to ich, Hexamita, and cottonmouth. These are parasitic infections that often grow unchecked. You should also look for:

  • Bloating
  • Weight loss
  • Inflammation of the gills and mouth

Using a list of observable symptoms should narrow down the culprit. Most aquarium diseases can be resolved with quick action and the right medication.

Angelfish Died After Changing Water

Did your angelfish die after you changed the water? Then you need to look at how you are performing water changes.

  • Are You Using A Water Conditioner? If not, you should. These neutralize the chlorides and other purifying chemicals found in our water. Otherwise, they burn the delicate gills of the fish.
  • Temperature-Match The New Water. A sudden change in temperature can put the fish into shock.
  • Do Not To Disturb The Substrate Or Gravel. As you pour the new water in, this can kick up debris and fecal matter.
  • Don’t Change All The Water At Once. The water must be given time to properly rebalance (with you monitoring the chemical changes as you do). This is done easier when you change a little at a time.

Angelfish Keep Dying But Water Is Fine

What if you checked all the water parameters and the fish are still dying? If the water isn’t at fault, the issue may lie with your fish themselves.

Are The Fish You Bought Unhealthy?

Not all fish breeders and sellers care about producing healthy fish. They may breed and sell sickly, weak, or injured fish en-mass. That will result in you bringing home that fish and watching it die unnaturally fast. Carefully observe the fish you intend on purchasing.

  • Does it appear healthy and well-fed?
  • Is it behaving normally?
  • Does its current holding-tank look healthy?
  • It is old?

There’s nothing wrong with perusing online to double-check your sources. The aquarium shop or online vendor should have some information available. Customer reviews are a goldmine when trying to spot poor business practices.

Are The Tank Mates Compatible?

Angelfish are known for being feisty. However, when housed with compatible tank mates, angelfish aren’t likely to kill other fish – or each other. That makes it important to properly research the fish that share a tank with your angels. If you pick wrong, everyone involved may get killed in the resulting conflicts. 

Angelfish can be both prey and predator. Large African cichlids and Oscars will prey upon angelfish. Male angelfish are also more likely to fight with each other.

Are The Fish Stressed?

Stressed angelfish can both hurt themselves and be more susceptible to illness. There are multiple factors that can stress a fish out. These include:

  • Incompatible tank mates
  • A tank that’s too small
  • Mating season
  • A lack of hiding places

If you’ve determined the water is fine, then another issue is at fault. Observe your fish.

  • It is darting around the tank?
  • Is it swimming up and down along the glass sides?
  • Is it hiding all the time?
  • Does it appear to be frantic?

Then it is likely stressed. You should try to give it more hiding places, a bigger tank, or try to prevent mating.

Can Angelfish Die From Over-Feeding?

Fish will eat themselves sick, so it’s up to you to ensure they are provided with the correct amount of food. Over-feeding fish can result in:

  • Impaction
  • Constipation

This will cause all sorts of problems in angelfish. You may notice the fish looking bloated or swimming abnormally if it is being over-fed. Likewise, over-feeding may result in excess waste in the tank. This can cause bacteria colonies and algae to grow out of control.

Look at the type and amount of food you are providing your angelfish with. If it’s freeze-dried or dehydrated food, then consider pre-soaking the food in the water. This stops it from bloating in the fish’s stomach. The same concept applies to flake and pellet food types.

Only provide the fish with enough food that can be eaten in 2-3 minutes. Any food that’s left over should be removed and disposed of. You can also begin including cooked peas or brine shrimp in the angelfish’s diet. These help with digestion.

Can Angelfish Survive In Cold Water?

As tropical fish, angelfish prefer warm waters. Although they will tolerate colder waters, they thrive in temperatures between 78° F – 84° F. To do this, you definitely need a heater to ensure consistency is maintained. Tanks that are too cold will see two things happen:

  • The angelfish will appear sluggish and inactive
  • They will struggle to digest food properly

This will see the fish dying off as their bodies clog with undigested food. That will lead to bloating and constipation, which can cause death within days. A very cold tank may even cause the fish to freeze to death.

Angelfish can tolerate small sessions with cooler water. For example, you may temporarily remove the fish from its tank for cleaning. Be careful to gradually acclimate it back to tropical temperatures to avoid shock.

Can Angelfish Survive In Hard Water?

Angelfish are able to tolerate water hardness outside of their ideal range. However, if this difference becomes severe, health problems will arise.

It is best to keep the hardness and acidity between 54 – 145 ppm and 6.8 – 7.8 respectively. You should only keep a different hardness if you’re accommodating the needs of different fish species. It should still be approached with caution.

There are plenty of home testing kits that you can purchase to test your water. You can also bring a sample (ideally, a full cup) of the water into an aquarium shop. Most will offer free or cheap water testing services. They can also test for a wider range of parameters.

Can Angelfish Survive Without A Filter?

Technically speaking, an angelfish can survive without a filter on its tank. However, this is risky. That’s because filters offer two primary functions:

  • Removing waste from the water
  • Agitating the surface

Both are vital for angelfish, unless very specific requirements are met. Experienced fish keepers may choose to not use a filter on certain tanks. This is only applicable when:

  • The tank gets weekly water changes of at least 20%
  • The tank is heavily planted and produces adequate oxygen for the fish
  • An air pump is in use
  • The tank has a small population and bio-load

Of course, maintaining an unfiltered tank is a lot of work. If you avoid keeping up with the waste and oxygen levels, the angelfish are very likely to die. An unfiltered tank also reduces the number of fish you can keep in the aquarium. You can only afford to have a limited bio-load in this case.

Can Angelfish Survive Without Oxygen?

Angelfish cannot survive without oxygen. That’s because they are classed as water-breathing fish. As described by Fish Physiology, it means that the gills are the primary site for gas exchange. Angelfish are not labyrinth fish, and thus cannot breathe gaseous air. They rely on oxygen that’s extracted from the water through their gills.

When there is a lack of oxygen dissolved in the water, angelfish will suffer hypoxia. This will lead to their body shutting down. Angelfish can survive a maximum of 12 hours without oxygen in the water.

To prevent this, aquariums need to dissolve oxygen into the water. This is done either with:

  • An air pump
  • A filter that creates surface agitation

You can also use plants to oxygenate the water. However, you should know that plants will only produce this gas if certain conditions are met. If you’re trying to switch your tank into a self-sufficient ecosystem, a lack of oxygen may be why the fish are dying.

angelfish death reasons

How Long Can Angelfish Survive Without Food?

Angelfish are a tropical fish with a relatively fast metabolism. As such, adults and juveniles will need to be fed 2-3 times a day. A morning and evening feeding is ideal. Ensure that you are feeding your fish enough food, the right type of food, and that all fish are getting enough food.

If not fed, angelfish will succumb to starvation in a little over a week, in most cases. Juveniles and fry will last half that time, if they are lucky. As you can imagine, starving to death is a slow, unpleasant way to die.

Anyone going on vacation or a work trip can get by with slow-release foods. These generally last for up to 2 weeks. 

Can Angelfish Survive In A Fishbowl?

Fishbowls are not an ideal aquarium for any type of fish, let alone angelfish. This species needs plenty of space, even if they’re housed without companions. Fishbowls are also difficult to attach heaters and filters to, which angelfish require. Angelfish will not survive for long in a fishbowl, and it is cruel to house them in one.

  • A single angelfish needs, at minimum, at least a 20-gallon tank.
  • Ideally, one angelfish should have a 30-gallon tank.
  • Increasing the number of angelfish in the tank will mean upsizing the tank by 15 gallons per fish.

Fishbowls are only suitable for dwarf shrimp, and only if the bowl is large enough. Even betta fish cannot live happily in a fishbowl, and require a 5-gallon tank.

Why Did All Of My Fish Die At The Same Time?

It’s a horrifying thing to discover that all of your fish have died in one fell swoop. A broad and sudden loss of all life in the tank usually points to a very specific number of problems.

Broken Heater

There are horror stories of cheap or old heaters exploding and “cooking” the fish. Sadly, this does happen from time to time. Usually, you’ll notice a very unpleasant smell before the worst happens. By touching the water with your hand, you’ll feel an obvious uptick in heat.

Investing in a quality water heater is worth the investment. You may need to replace it every 5 or so years.

Water Problems

As mentioned, improper water conditions may eventually kill all the fish at once. This includes everything from:

  • Too much ammonia and waste build-up
  • To a lack of oxygen
  • To a build-up of nitrates

Not cleaning the tank regularly also leads to this filth collecting in the filter and substrate. Should this muck be disturbed, it can release into the water and kill the angelfish.

Always treat water being added to the tank and perform regular water changes. These water changes should also only result in 20-40% of the tank’s water being replaced.


Angelfish can go into shock when water temperature suddenly changes. Even a water change with slightly too cold or too hot water can send all the fish into shock.

So, if you find that your heater stopped working and the fish are cold, don’t pour warm water into the tank. Get a new heater and slowly allow it to bring the temperature back to normal over several hours.

Improperly Cycled Aquarium

Be sure to allow a new tank to cycle for 3-4 weeks before adding any fish. This allows the nitrogen cycle to begin. This process is crucial. It’s where harmful ammonia becomes even more toxic nitrites, which then become benign nitrates. Without this cycle in place, harmful toxins are left in the water.

This will continue to build in deadly quantities. Adding fish before the cycle has formed will almost certainly kill the fish.

How To Keep Angelfish Alive

Like all fish, angelfish need consistent care and maintenance. If you want to avoid any sudden deaths, the best approach is to:

  • Set your tank to the right parameters
  • Change the water regularly, but with care
  • Feed your angelfish on a clear schedule
  • Watch out for signs of illness or infection
  • If sickness appears, separate and treat your fish
  • Invest in appropriate filtration, heating, decoration, and plants
  • Choose tank mates carefully

With these basic steps, you can lower the chances of your angelfish suddenly dying. As a plus, it will make your watery friends a lot more comfortable in their new home.