Do Danios Die Easily? 10 Reasons Why Danios Could Die

Do Danios Die Easily? 10 Reasons why Danios could die

Zebra Danios are small and very active fish, they are tropical and freshwater fish and are normally kept in the home aquarium by many people because of their colors, activeness, and also how hardy they are which makes them beginner-friendly fish. Also, they are less aggressive fish that lives in a group because they are schooling fish. Many people do complain about how they lost many of their Danios and this lead to the question, do Danios die easily? and why do they die?. In this article, you will learn why they die and what to do to save yours from dying.

Do Danios die easily? Danios are hardy fish and don’t die easily unless they are killed by another animal or by poor living conditions.

There is a reason why they are sometimes called beginner-friendly fish, it is because they are very hardy and are not usually affected by some minor changes in their environment such as temperature, pH, etc so they are easy to keep by almost everybody, including those with zero knowledge of fish keeping.

This is to say that Danios are strong fish and could hardly die unless some serious issues are going on in your tank, that’s why you may be losing them or they are becoming sick and dying.

I didn’t say they don’t die, it is normal to lose one or two in a school of more than 6, but if they keep dying regularly, then you might have to test their water with water Testing Kits to know what is wrong with them.

Now you know that they don’t die so easily, but what if they keep dying? well, we will look at the common reasons why yours might be dying so easily.

Why Do Danios Die?

There are many reasons why they might die despite being hardy fish, they are:

1. Overfeeding: You might be surprised at this, but overfeeding does kill many fish more than you might think.

This is very common among those that have little or zero knowledge about fish keeping.

The fact is, feeding is caring, but overfeeding is not! newbies think that they are caring for them by stocking their fish stomachs with lots of foods, but the effects could be very devastating.

One thing about fish is, that they will keep eating for the fact that you keep feeding them without minding if they are okay or not, so they have no limitation when it comes to food and will eat till they bloat.

Overfeeding can kill any fish through bloat by disorganizing their swim bladder which will lead to them swimming upside down, etc.

Again there will be many leftover foods or food particles which will breed toxins such as ammonia in the water, which is very harmful to any fish, including Danios.

Also, leftover foods will breed and feed algae in large quantities which will be sucking up the oxygen in the tank and also dirty the water, thereby making it unsuitable for the fish.

2. Poor Water Condition: Although Danios are hardy in nature, that doesn’t mean they should be treated and kept anyhow, no, they have their ideal water quality and parameters like other fish too.

When they are not in their ideal water quality and type it will weaken them and could even affect them negatively, which might lead to their death.

They are freshwater and tropical fish too, so they need to be kept in a warm temperature between 65-75°F and could tolerate up to 80°F, So they should be kept with a Heater.

Their ideal water parameters are pH should be between 7.0 and 7.8, and alkalinity between 3° and 8° dkH (50 ppm to 140 ppm).

They need to be in a tank with substrates such as gravel, sand, plants, and many hiding places such as caves, pipes, etc which will be keeping them busy and active all day long.

3. Toxins: Toxins are very deadly for almost all fish, including the hardy Danios.

Although there are toxins that are not very harmful and there are those that are very fatal to any aquatic animal that it might get in contact with, but in overall, no toxin should be allowed to develop in your fish tanks because if it happens, the lives of your fish are at stake.

Toxins such as ammonia, nitrite, nitrate, chlorine, and copper are all harmful to any water animal they get in contact with and might be the main reason why you might be losing your Danios.

There are many things that might cause these toxins such as the source of the water, especially pipe water, leftover foods and decayed organisms in the water, etc.

It is recommended to check or test your aquarium water at least once a week with Water testing kits to know if any toxin is in the water.

4. Uncycled Tank: Just like toxins, uncycled tanks are very harmful to any fish and even to other aquatic animals.

Tank cycling is the process of leaving a new tank to get rid of harmful chemicals and toxins in it to breed friendly bacterias which would not harm any animal that will live in it.

This process is very important, but many people, especially newbies do ignore it and they always pay heavily for it.

The fact is, an uncycled tank could kill all animals you keep in it in a short while or even make them sick, and it could be the reason why yours are dying, especially in their numbers.

Many people do keep a fish in their new tanks and leave the tanks to cycle with the fish, well, I strongly object to that! the fishless cycle is what I recommend because I see it as cruel to use a living animal to cycle a tank.

Some tanks take up to a month and 2 weeks to fully cycle and some take less than that, so always test your water to know when the tank is ready.

5. Stress: It is a fact that all fish hates stress, including aggressive fish too.

Stress could affect any type of fish negatively and could even be the reason your Danios are dying.

There are many agents of stress such as Toxins and Chemicals in their water, unsuitable tank mates, wrong water parameters, dirty water, lack of hiding places, etc.

All of these could cause stress which will weaken their immune system and make them susceptible to any kind of diseases which they might die from.

Although Danios being hardy might not die directly as a result of stress, but it could make way for them to be affected by diseases that could kill them.

6. Unsuitable Tank Mates: If your Danios are dying or missing, you may have to check the level of aggression going on in the tank.

This is because it is possible that other fish or animals are stressing them to death or even eating them.

It is not advisable to keep Danios with aggressive fish because they may be eaten or their fins and tails nipped which could result in fin rot and their death.

If you must keep them with other fish, keep them with less aggressive fish of their size and not those that are bigger than them for them not to be eaten or stressed to death.

7. Danios will die if they are not kept in large numbers: As we all know, Danios are schooling fish and no schooling fish can be able to survive all alone or in small numbers.

They do need each other to be happy and survive, that’s why they are normally seen in groups and they don’t move alone.

Although they might fight each other, especially the males to show dominance, but they don’t live without each other.

Because of this, the recommended number of Danios to keep in a tank is 6 and above.

So, if you have less than 6 in a tank, then that might be the reason they are becoming aggressive and dying.

8. They are old: Every living thing has its lifespan, including fish too and when it elapses, the animal will die.

The average lifespan of Danio fish is 5 years, depending on how they are being cared for, and when they reach the limit of their lifespan, they will die.

According to research, those in the wild live longer than those in captivity, this could be because of the type of environment they are exposed to or the food they eat.

So, if yours are dying, then you might have to check their age and find out if their lifespan has elapsed or they died of a different cause.

9. Diseases: Danios are not immune to diseases despite being hardy in nature.

There are many diseases that might infect and kill them if precautions are not taken, such diseases include: a hole in the head, columnaris, gill disease, ick (ich), dropsy, tail and fin-rot, fungal infections, white spot disease, pop-eye, cloudy eye, swim bladder disease, lice, and nematode worms infestation, water quality induced diseases, constipation, anorexia, etc.

So, watch out for diseases and when you notice that they are behaving very strangely, then you might have to contact a veterinarian doctor for medication and medical advice.

10. Tank size: Lastly tank size is another factor that might lead to the death of your Danios.

So many people make the mistake of placing these fish in smaller tanks like 5, 10, and even 20-gallon tanks. This is very wrong.

Despite that they are small in size, they are very active and loves to be in large number, so they deserve to be kept in a tank of not less than 55 gallons for them to feel full freedom.

When kept in a small tank, they will become aggressive and will start attacking each other, biting each other’s fins which could lead to fin rot disease and death.

How To Prevent Danios From Dying

To prevent them from dying, all you need to do is to be very careful with them and provide them with all they need which includes their ideal environment.

Tips to keep them from dying are:

1. Feed them once or twice a day and with a little quantity of food that they can be able to finish in 2-3 minutes to avoid overfeeding them.

Once you overfeed them, you might have to starve them for a day or 2 so that they can defecate the ones they have eaten and free themselves.

2. make sure you give your new tank enough time to fully cycle and avoid cycling with live animals too.

As I explained above, sometimes a new tank could take up to a month and some weeks to be fully cycled, so you need to have patience.

3. Always test their water with testing kits and do a change of water if you detect any toxin in their water. Detoxifiers could help to neutralize any toxin in the water such as Ammonia. Although when you use a detoxifier, your testing kits could continue to detect toxins, but it is alright and they are now neutralized and won’t affect your fish.

4. Do a weekly change of water and avoid stressing them with it.

Although a change of water is good, but it could harm them in some cases, so I recommend you do nothing more than a 30% chance of water every week.

Buy both filter and air stone to keep the water clean and to supply enough oxygen all over the water.

5. Avoid getting them in a tank with aggressive and bigger fish to avoid bully and possible cannibalism in their tank.

6. Always keep your eyes open for any disease and get in contact with a vet immediately if you notice any sign of disease.

Also, avoid mixing captive-bred with wild-caught Danios because they might be moving about with diseases that your captive-bred cannot be strong enough to handle.

Why Are My Glofish Danios Dying?

Glofish Danios could die as a result of poor living conditions and as a result of aggressive tank mates.

Glofish Danios, just like other Danios like the zebra Danios, leopard Danios, etc could be dying as a result of all the factors I listed and explained above.


Danios are hardy fish and don’t die easily, unless something is wrong and the above are the reasons why they might die, so check yours and find out the reason behind their sudden death and stop it by yourself or seek the advice of a Vet.