Guppies are known as amazing beginner fish. If you happen to have issues with them, you might catch yourself thinking, “Why are my guppies dying on me while everyone else is having an easy time with them?”
The truth is, while guppies are fairly straightforward to keep, even experienced fishkeepers will eventually end up with some dead fish. These fish can even be guppies.
No fish is so hardy that nothing can happen to it, especially if you’re new in the aquarist hobby. Even I wondered why my guppies are dying more often than I’d like to admit!
There are numerous causes behind the death of fish. Over time, though, I’ve realized it usually comes down to 11 reasons – at least when dealing with guppies.
Keep on reading if you want to find out what they are.
Why Are My Guppies Dying?
If you wonder ‘Why are my guppies dying?’, there are many factors you need to consider.
First of all, you need to look into the entire situation. Are you keeping a single species in an aquarium, or are you having a community tank?
If you’re having multiple species in a single tank but it’s only the guppies that are dying, chances are the water parameters aren’t suitable for them but are okay for other fish. Another option is tank mate aggression, as larger fish might kill or eat smaller guppies.
If you’re only keeping guppies and they’ve started dying, then the list of choices isn’t that narrow.
Either way, here are 11 reasons that are likely the reason behind the death of your guppies:
1. Acclimation Issues
Did you just introduce guppies to your tank, but many of your new fish have started dying? If this is the case, your guppies are probably having issues getting used to their new environment.
You probably know that you should leave the bag with new fish inside the future guppy tank for at least half an hour. This will prevent temperature issues, so your fish will acclimate much easier. As such, it is unlikely that the difference in temperature caused any problems.
As I believe you have made sure the ammonia, nitrite, and nitrate levels are proper, the main culprit is probably the difference in pH levels.
While guppies can acclimate to a fairly wide range of pH values, if there is a sudden change in pH, they might get sick and die. A general rule of thumb is that the difference in pH between the new and the old water shouldn’t be greater than 0.2.
Anything larger than that might be the reason why your new guppies are dying.
2. Wrong Ammonia Levels
Guppies are more sensitive than many people think, especially when it comes to ammonia levels. Even the tiniest ammonia spike might wreak havoc in your tank.
The main ammonia source inside your tank is fish waste. If you don’t have enough ammonia-eating bacteria inside the tank, the ammonia levels will rise, which is toxic to guppies.
In a well-established tank, ammonia levels should be 0 ppm. Anything larger than 0 might compromise your guppies’ immune system, leading to health issues and death.
You won’t be able to notice high ammonia levels just by the naked eye. However, the impact ammonia has on fish might be rather noticeable, and this includes:
- Increased mucus production,
- Guppies’ scales become darker,
- Inflamed gills,
- Bloody gills,
- Gasping,
- Increased infection rate.
If you don’t lower the ammonia levels quickly, this can result in the death of your guppies.
3. Wrong Nitrite and Nitrate Levels
Another water parameter you need to monitor constantly is nitrite and nitrate levels.
Nitrate is fairly stable and doesn’t cause too much harm unless the levels go overboard. In general, as long as they’re under 40 ppm, they won’t hurt your guppies. However, a sudden nitrate spike might harm your guppies.
Nitrite, on the other hand, is very toxic even in the smallest amounts. You should always make sure its levels are 0 ppm. Even trace amounts of nitrite can harm your guppies!
As such, if you notice your guppies are dying, make sure to test nitrate and nitrite levels, as well.
4. Improper Cycling
Before you can add fish to a new tank, it needs to go through the nitrogen cycle. This is a natural process that enables the growth of good bacteria.
While a regular cycle usually lasts for 4 to 6 weeks, there is a way to cycle your tank in just 24 hours. Unfortunately, these instant cycles are usually where it goes wrong.
If you’ve failed to properly complete the tank cycle, your guppies might die. Their death will usually occur in a matter of days, if not hours.
Even if the cycling process lasted for several weeks, always use a testing kit before adding the fish. This is the only way to prevent a disaster.
5. Bad Temperature Range
Guppies are tropical fish. They can withstand a fairly wide range of water temperatures, but they’ll thrive in warm water. Cold water might compromise their immune system, increasing their chance of illness.
The ideal water temperature for guppies is between 72 and 82 degrees Fahrenheit. Just because they can survive in lower temperatures, doesn’t mean they should live in such conditions.
The only way to ensure your guppies live long and healthy lives is to keep the water within a specific range.
While guppies won’t immediately die if the water temperature isn’t proper, this will further increase the impact of any other issues that might be occurring.
6. Low pH Levels
No fish can thrive in hard water with low pH levels – however, livebearers are especially sensitive to acidic water.
The ideal pH levels for freshwater fish such as guppies are between 7 and 8. However, never put guppies in water that has pH 7. This is because fish waste lowers pH over time, so the water can reach dangerous levels rather quickly.
Next to choosing the right water parameters, never use old and dirty filters. Not only will this disrupt the pH value of the water, but it will also lower oxygen levels, making it a dangerous combination for your guppies.
If you’re having trouble maintaining proper pH levels, don’t worry. There are many ways to raise pH levels in your water, either naturally or by using chemicals.
7. Low Fry Survival Rate
Guppies are known for their fast breeding. They are livebearers with fairly short gestation periods, so you’ll quickly have lots of new guppies inside your tank.
However, you’ll probably notice that fish fry tend to die at a much faster rate than adult guppy fish. There are a few reasons behind this.
First and most common reason is that baby fish tend to become live food for larger fish. Even their parents might mistakenly kill them!
This is why it’s recommended to have a proper guppy fry tank when you notice your fish will give birth. A 40-gallon breeder tank might do the trick!
Another solution is to provide your fry with a bunch of hiding spots. Live plants might be a great option, as they’ll give the little fish better chances of surviving into adulthood.
Fry fish also have weaker immune systems, so they’re more prone to health issues caused by lack of maintenance or improper parameters. They’re also sensitive to lack of oxygen, so water testing kits and regular water changes are a must.
8. Stressed Out Females
While this one might sound funny, this is usually the main problem for most guppy owners. It’s important to understand the instincts of your fish.
Just like with all other animals, guppies’ main instinct is to breed – especially when talking about males. Male guppies are no different – they’ll want to mate all the time!
If you have too few female guppies, males will chase them all the time. This will lead to their exhaustion, and eventually, it can kill them.
It’s essential to keep two females for every male fish. This will give your male guppies plenty of options, so they won’t constantly chase the few females that are in their company.
9. Unsuitable Tank Mates
Guppies are friendly fish. They aren’t likely to attack other fish, which makes many novice fishkeepers think they can live with most water critters. However, this isn’t always the case.
First off, while guppies are friendly, larger fish might view them as food. This is probably obvious; carnivorous fish will eat anything much smaller than them.
Also, some fish make aggressive tank mates. Peaceful guppies don’t know how to fight with them, so many will die if you keep them with fish species that aren’t as friendly.
Another behavior not many fishkeepers think of is rivalry among fish species. Most fish with long, trailing fins will feel like guppies are their rivals. As a result, they’ll nip at their fins, hurting them, which can result in the guppies’ death later on.
As such, I wouldn’t advise you to keep guppies with fish such as bettas and gouramis. Instead, pick fish such as mollies, or even small animals such as bumble bee shrimp or blue tiger shrimp.
10. Health Problems
Unfortunately, guppies are not the healthiest breed. They are prone to many health issues, mainly due to poor breeding practices I’ll mention in a bit.
Also, many fishkeepers tend to keep guppies in overcrowded tanks, which increases the chances of disease outbreak.
Most common diseases guppies deal with include fin rot, flukes, and gold dust. Guppies are also prone to the White Spot disease, caused by the Ichthyophthirius parasite.
11. Bad Genetics
Sadly, many issues regarding short guppy lifespan lie in their genetics.
Many guppies, especially colorful morphs, have bad genetics due to inbreeding.
In order to create colorful morphs with long fins and unique scale shade, breeders allow fish from the same family to breed. This results in many genetic diseases and short life expectancy as the gene pool is no longer diverse.
If you are certain you’re doing everything right but still see many of your guppies dying, chances are this is the issue.
Unfortunately, the only way to prevent poor guppy genetics is to buy common morphs that aren’t challenging to breed. While even this isn’t a guarantee your guppies will be healthy, it significantly decreases the chances of fish being born with various genetic conditions.
Also, look for breeders that are known for their ethical breeding practices. They keep guppies from the same strain separated to prevent them from inbreeding. However, most aquarium owners will simply buy guppies from pet stores, so I am certain not many people will do proper research.
How Do You Save a Dying Guppy Fish
Unfortunately, there is little you can do if your guppy fish is already dying. The good news is, if you happen to notice your fish look sick, you can do all you can to improve the conditions it lives in. This will greatly increase the chances of survival.
You can also get antibiotics for your fish, or even use a bit of aquarium salt. If you don’t have aquarium salt at hand, there are a few homemade recipes and substitutes you can try.
Of course, good care is the best way to ensure your guppies live long.
To prevent the acclimation issues, test the water parameters inside the bag or the tank the guppies came in, as well as in the main tank.
If the difference is fairly large, just add a bit of the old water into the new tank. Once you have about 1/4 of the new water and 3/4 of the old one, your new fish should be fine.
Regular tank maintenance is also very important, just as proper feeding. Don’t give your guppies too much food, as the rotting food will increase the ammonia levels.
Avoid tap water whenever possible. Next to being hard and having improper pH levels, tap water contains lots of chlorine which can be toxic to fish.
In general, if you manage to keep your aquarium water clean and take good care of your guppies, you’re unlikely to see them dying any time soon.
The Final Word
While guppies were known as some of the most amazing fish for beginners, sadly, this is no longer the case.
Bad breeding practices and uneducated tank keepers have shortened the lifespan of these adorable creatures, and now many people are wondering, ‘Why are my guppies dying all of a sudden?’
Unfortunately, you cannot help fish with bad genetics. However, you can do all you can to provide them with the best lives possible.
Of course, before you can conclude your guppies are dying due to terrible breeders, it’s important to rule out all other causes of death. Make sure to test water parameters and observe your fish’s behavior.
Finally, if most guppies from your aquarium have died, I would suggest emptying the entire tank and giving them a new start. Sometimes this is the push in the right direction they need.
You know that calming feeling of tranquility and thrill while looking at a gorgeous, perfectly functioning tank? That’s why I became an aquarist.
To make a very long story short, I’m Noah, and I’ve started this site aiming to share the most helpful advice on creating thriving habitats for fish and underwater animals.