9 Reasons Why Guppies Die (And How To Prevent Them)?


Guppies are very popular fish because of the energy and color they give aquariums.  So it’s quite disappointing when they lose that energy or worse, die.

So why do guppies die easily?  These can be because of:

  • Poor water quality
  • Fights with tankmates
  • Birthing
  • Too much inbreeding
  • Old age
  • Internal parasites
  • Dropsy
  • Overmedication
  • Accidental poisoning

Guppies are the perfect kind of freshwater fish to keep in your aquarium because they’re colorful, fun to be around, relatively easy to take care of, and inexpensive.

That doesn’t mean, though, that you’ll neglect the basic necessities of an aquarium fish, such as a cycled tank.

How Do You Fix Poor Water Quality In A Fish Tank?

Let’s discuss some basics of maintaining a good water quality for our Guppies.

Do You Need To Cycle A Guppy Tank?

Caring for fish doesn’t mean buying the tank and the fish all on the same day.  If you do that, your Guppies will pollute the water with their waste and end up dead in 5 days or less. 

Yes, Guppies need a cycled tank.  Cycling a new tank simply means creating the nitrogen cycle in the water.  This is necessary to break down substances like ammonia and nitrates produced by fish waste—substances that are toxic to your fish.

Imagine yourself living in a dumpster or compost pit and breathing its air day in and day out.  Can you survive that?  Neither will your Guppies in uncycled water.

The system of a cycled tank is the perfect water quality that Guppies need in order to survive.  It’s like having fresh air to breathe for humans.

How Long Should You Let An Aquarium Cycle?

Cycling a tank takes some patience as it cannot be done in a matter of hours.

Cycling your fish tank may take 2 weeks, or it may take as much as 8 weeks.  It depends on how fast your tank reaches the point where nitrates are produced (the end of the cycle). 

If you’re so eager to put your fish in and your tank isn’t completely finished yet, your Guppies will certainly die.  It’s best to wait until the cycle is done when levels are no longer lethal to your Guppy.

9 Reasons Why Guppies Die
9 Reasons Why Guppies Die (And How To Prevent Them)?

What Water Conditions Do Guppies Need?

Dirty water is almost always the reason why Guppies die ahead of their time. 

The water parameters that Guppies need in order to stay healthy are:

Water ParameterCorrect Level for Guppies
Ammonia0ppm
Nitrate0ppm
Nitrite<40ppm
pH6-7.5
Hardness8-12dGH
Temperature74-82 deg F

How Does Poor Water Quality Affect Fish?

Changes in the correct water parameters for Guppies may poison your fish, compromise their immunity, and make them prone to diseases.

Some of the reasons for poor tank water quality are overfeeding and overcrowding (or overstocking) of fish.

Consistency in water quality is key to keeping Guppies healthy.  Ammonia poisoning may happen if levels spike up, causing your fish to get stressed.  This makes them vulnerable to different types of diseases.

What Happens When You Overfeed Guppies?

Now that your water is okay, you might be pretty excited to see your Guppies healthy and active.  But that doesn’t mean you should be overloading them with food.

Overfeeding leads to overproduction of waste, and that causes ammonia levels to spike up.  If there’s uneaten food sinking to the bottom of the tank and not cleaned regularly, that becomes waste as well.  Rotten fish food leads to the same thing: a rise in ammonia levels. 

These excess bio-loads will push nitrites and eventually, nitrates up, too.  Before long, your nitrogen cycle has crashed and your Guppies start to get sick.

Besides, overfeeding may also lead to constipation and bloating.  And that is another danger to your Guppies.

So now you’re keeping your pets happy with good water and good food.  You’re so pleased that you want to add more Guppies in the tank.  The more, the merrier, right?

What Will Happen If An Aquarium Gets Crowded With Fish?

Guppies are usually kept in groups.  They are also great fish to keep in a community tank along with other peaceful species.

But too many fish or Guppies in a tank mean more fish pooping and eating.  The bacteria in your tank won’t be able to keep up with the high production of ammonia, causing your cycle to fail.

What Are The Signs Of Ammonia Poisoning In Fish?

If you’re not aware that your ammonia level is rising, your fish may be able to tell you when it exhibits certain behavior.

Guppies that have ammonia poisoning have red or inflamed gills.  They’ll stay at the surface of the water or near bubbles of water gasping for air.  Your tank water may appear murky.

Ammonia poisoning is not a disease, but it stresses your Guppy enough to make it susceptible to various diseases.

Stress in Guppies lead to bacterial and fungal infections, fin rot, ick, and other similar diseases.

How Many Guppies Should Be Kept Together?

Well, it depends on the tank size.  Guppies like to swim a lot so they would appreciate a lot of room.

If you have a 5-gallon tank, a trio of 2 females and 1 male Guppy should be fine.  But having a 10-gallon tank for your trio is even better.

If you get more confidence and experience with taking care of Guppies, you can even up that number to 5 Guppies in your 10-gallon tank.  Be careful with more, you know you’ve put too many fish if they start nipping and fighting.

A Guppy tank with males and females can also result in pregnancies at some point.  If the mother Guppy isn’t moved before giving birth, adult Guppies in the tank might eat the fry.  If a lot of fry survive, we’re back to the same issue: overcrowding.

Can A Guppy Kill Another Guppy?

When a tank is overcrowded, there is a tendency to fight for space among fish.  This is not only true in a male-only tank, but also in a community tank where there might be other species of fish that are present.

Yes, there are times when Guppies fight each other to the death.  Guppies are not supposed to stay in a male-only tank as they’re always looking to mate.  The non-presence of females will prompt Guppies to attack each other for dominance and territory.

Make sure you keep that ratio of 1 male to 2 female Guppies in your tank to lessen the stress and territorial attitude.

Why Did My Guppy Fish Die After Giving Birth?

Now that we’ve mentioned Guppy pregnancy, it’s also important to note that Guppies have complicated pregnancies, too.

Female Guppies sometimes die after giving birth mostly due to stress and pregnancy complications.

Pregnancy complications among Guppies include fry getting stuck in the birth canal.  There have been instances when it has been hours and the wiggling fry or underdeveloped embryo can’t seem to fully get out of the mother.

Mishandling the pregnant Guppy may also lead to stress during childbirth.  Or sometimes, the water parameters in the breeding tank aren’t as ideal as they should be. All these can contribute to the death after or sometimes even during childbirth.

Is Inbreeding Bad For Fish?

Now that we’re on the subject of breeding, we have to understand that sometimes, Guppies die easily because they were born with low immunity.

Since Guppies are not as brightly-colored in the wild, the Guppy trade is made up of inbred fish produced by parents paired up purposely for their attractive traits.  Breeders do this to create more sellable fish.

Inbreeding in itself is not bad to Guppies as it helps to preserve the desired traits in fry.  However, too much inbreeding results in fry having a higher chance of exhibiting slower growth rates, lower fertility, weaker immunity, shorter lifespan, and sometimes deformities. 

To avoid producing weak Guppy stock, the best thing breeders can do is to perform outcross breeding once in a while.  This will help the next generation to be more resilient and live longer.

How Many Years Can A Guppy Live?

Regardless of the type of stock, Guppies will die of old age at some point.  It doesn’t matter how good you cared for it, pets won’t live forever.

Guppies live an average of 2 years.  The most anyone has kept them in captivity for is said to be about 4 to 5 years.

You might’ve bought a healthy Guppy that was 4 to 6 months old.  You brought it home and properly cared for it, but it still died without symptoms of disease a year or two later. 

If this is the case, then there’s not much of a mystery.  It was most probably it’s time to go to pet heaven.

If there were symptoms, that’s another story.

Can Guppies Get Parasites?

It’s not uncommon for new pets to have contracted something from the pet store.

Guppies are susceptible to internal parasites, including the Gyrodactylus turnbulli fluke, the Dactylogyrus fluke, the Camallanus worm, and the Ichthyophthirius multifiliis (ick).  All of these are contagious.

Female Guppies are also more susceptible to contracting parasites from other fish because they are more known to shoal or form socializing groups.

How Do You Know If Your Fish Has A Parasite?

One indication of the presence of internal parasites is that the Guppy’s poop will be stringy and clear.  They can also be flashing, or scraping themselves against the sides or the tank or decors within.  In the case of ick, there will be white spots and/or red lesions on the Guppy’s skin.  The fish might wiggle or shake.

Guppy poop becomes clear because the parasites eat what’s inside the Guppy’s intestine, taking away needed nutrition.  This causes the Guppy to be lethargic and have a sunken belly.

Healthy Guppies don’t wiggle but swim gracefully all around the tank.  They may dart every now and then (which is normal), but not shake.

As the parasites multiply, they’ll start eating the Guppy from the inside.  Without treatment, organs will shut down and eventually kill the Guppy.

Early diagnosis is key, so that the fish can be separated into a hospital tank right away so as not to contaminate others. 

How Do You Treat Parasites In Guppies?

Treatment should be administered to the isolated fish.  The earlier you find out about the disease, the more effective the treatment will be.

Add a teaspoon of salt to every gallon of tank water.  Slowly raise the temperature to 80 deg F.  Make water changes more frequent.  Additionally, you can peel a clove of garlic and leave it at the bottom of the tank so the juice will kill the leeches.

If the parasites are persistent, you can give your Guppies levamisole and praziquantel.  Two weekly doses should be enough to kill the parasites and the babies that might have hatched while they were inside or latched on to the Guppy.

Clean your main tank, too.  That will kill any parasite left behind that could be clinging to plants, decors, and substrate.

In the future, make sure the Guppy you bring home is disease-free by observing a 1 to 2-week quarantine period.  This will help other fish to avoid the disease as well.

What Causes Dropsy In Guppies?

If your Guppy gets bloated and exhibits signs of pine coning, that’s definitely dropsy.

Guppy with dropsy
Guppy fish with dropsy disease

Dropsy is a symptom of any number of diseases in a Guppy’s internal organs including bacterial, fungal, and parasitic infections. 

Dropsy might’ve been brought by a new, non-quarantined fish in the tank, or they might’ve been caused by spikes in ammonia levels, a drop in water temperature, or it might simply be stress.

Dropsy is a high mortality disease, meaning, most fish that acquire this disease won’t survive it.  This is especially true if the sickness wasn’t diagnosed and treated right away.

How Do You Fix Guppy Dropsy?

If the sickness is not severe, the Guppy might still respond to treatment.

Dissolve a teaspoon of Epsom salt into the tank water and add it into the aquarium.  Check your water temperature and make sure it is within correct levels.

If symptoms persist, try a broad spectrum antibiotic like maracyn-2.

Can You Over Medicate Fish?

The reason why Explore Fish World encourages the use of natural remedies first is to avoid poisoning from the use of too much or the wrong medicine. 

Accidental poisoning of Guppies may happen with improper use of medication.  Doubling the dosage won’t hasten Guppy recovery.  And habitual use of medication makes fish immune to them.

Diseases can sometimes be misdiagnosed without the guidance of a trained eye.  Ask a vet or an experienced breeder if you need more information.

If you’re using medicine to treat your fish, do extensive research first and follow the correct dosage carefully.

Keep your tank cover clean of any substance that might spill and kill your Guppies.  That includes chemicals you use for water testing.

Accidental Poisoning Of Guppies Water Tank

What Chemicals Can Kill Fish?

If your Guppy died mysteriously, it’s time to go CSI and do a little investigating.  If you can’t find clues inside the tank, the culprit might be outside of it.

Household chemicals may become toxic to fish if they find their way into the tank.  These include strong air fresheners, flea spray, spray deodorants, or that dishwashing liquid residue on your hand which you used to handle your fish.  This is called environmental poisoning.

Most of these are sprays that you might use in your room.  Since fish get oxygen from around the tank, be concerned with what chemicals are present in that air.

Can Too Much Aquarium Salt Kill Fish?

Yes.  Salt causes dehydration in fish.  Putting salt directly into your tank can burn their gills.

In cases of overmedication or over-salting, more frequent water changes is the solution.

FAQ About Guppies

What are the signs that my Guppy is sick?

Aside from the symptoms mentioned above, here are a few more you would want to watch out for in your pets or would-be pets.

  • Weight loss and loss of appetite are indicators of poor health.  Try and spot a skinny Guppy from on top of the aquarium.  A healthy fish has some meat on the head and tail, the skinny Guppy is just flat and straight. 
  • Guppies aren’t supposed to swim in the middle of the tank with their fins closed.  They usually swim with their fins open and free.
  • Stress markings, loss of color, or sudden increase in color may be indicative of chemical poisoning.

Should you remove dead fish from aquarium?

We’re very sorry that your Guppy died, we know you did everything you could if you’re reading this.

Dead fish should be removed from the tank right away as its body can rot and affect water chemistry for the remaining fish.  If it died from some disease, you should remove it quickly to avoid other fish consuming its remains and contracting the same sickness.

Why Guppy fish die?
A died Guppy fish

After removing, test the water to make sure it’s not already polluted.

Are Endlers hardier than Guppies?

Good thing you asked.

If you’re looking for a hardy Guppy, try Endlers.  They’re wilder and smaller, but are less affected by diseases compared to the common Guppy.

Because Endler Guppies are wild, they’re more active inside the aquarium.  That can be fun to watch, but they also love to hide more under plants and decors.

Care for the Endler Guppies are very similar to the common Guppy.  They even eat the same food.

The Endler is a littler pricier than the common Guppy, though, but that also means you’ll get more profit if you’re interested in breeding it.

We know you love your Guppies, and we’re glad to help however we can.  If you learned something new from this article, or if you need a question answered, shoot us a message.

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