Why Are My Guppies Dying: Causes and Prevention

Guppy fish can be purchased at most pet stores. They are small, colorful fish that live in tropical or subtropical environments. The guppy is known for its playful personality and intelligence. They are easy to care for and are popular pets in many countries. But like other pet fish, the health of guppy fish as well as its longevity in so many factors.

In this article, we are going to discuss the most common causes of death among guppies and also take a look into some of the best tips to prevent diseases and death.

Why Are My Guppies Dying?

blue grass guppy is beautiful tail.

Some of the leading causes of death among guppies include:


Over feeding your guppy can cause fish to breed too frequently and make it difficult for them to develop properly as well as have difficulty in finding food sources. They will also become aggressive, making some lovely pets into unwanted pests which makes them more likely to live longer than their short lifespan if they aren’t overfed. Keeping your tank clean is also a top way to prevent death caused by cleaning it.


Under-eating of your fish is another major cause of death among guppies, making them weaker and more prone to disease which makes these aquatic creatures more likely to die sooner than expected if they don’t receive sufficient amounts food in their tank regularly enough. In addition, malnutrition causes immune system shortcomings as well which increases the chances that infections may occur leading to possible deaths.

High Temperatures

High temperature can kill guppies very quickly just like other fish and only killing a few hours after they have been exposed to high temperatures. It is important not to leave your aquarium in direct sunlight too often, especially during the summer seasons because of this reason. It should also be kept out of direct sunlight or covered with something if possible (i.e., small glass jars placed underneath or plastic wrap) if your home has tropical weather.

Poor Water Quality

One of the worst things to do when taking care of fishes is keeping their habitats free-flowing and clean with crystal clear water. All it takes for your aquarium water to start degrading into a sooty hue or clouded up, can be from a single microbe that proliferates through excess nutrients (also known as nitrogen), decaying matter, dead fish, uneaten food or bacteria which may accumulate within your tank. The water your pet fish has been living in is just as important to their lives as the food they get, so maintaining a clean and healthy environment will help you care for them better with less stress on both of you so that growth can be more quickly achieved!

Ammonia Level

Ammonia is a water pollutant that can produce harmful effects on your pet fish over time if you have poor filtration and frequent ammonia spikes . The levels of ammonia gas in your tank determine the number of diseases you may encounter, so take care to monitor where this chemical falls. Since it is easy for guppies to pick up disease, it is also important not to overcrowd their space because these oily-skinned slippery critters are not the friends of bacteria or viruses. Carbon and biological filter can do a lot to keep aquarium water clean and help with removing waste that is otherwise left behind in these tanks (fish poop, uneaten food), so being sure you have one in place will be key to your fish’s health.


Overcrowding in fish tanks is bad because one single pet fish need a maximum of 1 gallon for at least 2 gallons. This means pretty much your guppy is living in a small space, which can be quite difficult to swim around intricate and large aquarium gravel places as they wouldn’t have enough room to operate at all which puts them under stress constantly. Overcrowding only exacerbates the problem by placing a greater number of fish in one or maybe two tanks, losing more natural boundaries (babies tend to explore beyond their designated territory) which can lead not just overpopulated but polluted aquariums due themselves into diseases because bacteria get confused with this close quarters/temperature/water quality issues. 

Diseases & Parasites

Aquarium diseases and parasites can spread from one guppy to another quickly. Keeping your guppies healthy will make the lives better for them as well! The best way you can do this is by careful selection criteria before adding any new fishes into your tank or habitat (discard all dead/unwanted ones). Guppies are cousins to many damsels in stripes such as live bearers and comb fish, both of which tend to feed a lot and generally suffer from this same common problem.

How To Prevent Sudden Death in Guppies?

Guppy Multi Colored Fish on a black background with green algae.

Proper Feeding

Feed them a diet consisting of vegetables, grains and protein-rich foods like bloodworm or brine shrimp. If the guppies have just been introduced into their new aquarium it will be much harder for them if they receive anything less than 1-2 days worth of food in one feed (don’t give carnivores anything but veggies until it’s been a week). Keep your guppies well fed and alert. Many fish go into bouts of “fever sickness”. They may flip around in their aquarium thinking that something is on the end of them causing all kinds of delusion, or they may have just eaten too much food and become sick from it.

Maintain Good Water Quality

One of the most basic steps to keep your guppy fish healthy will be maintaining a pH of 7.0-7.2 for your water (depending upon very large variation depending whether alkaline or acidic) by adding only high quality aquarium salt, mineral supplement and daily maintenance water changes to keep it at proper water chemistry. In this manner, you will prevent many forms of disease from attacking your pet fish.

Know How They Adapt

Guppies are early adaptors to new surroundings and so a sudden change in their conditions can be the culprit of many fish deaths. Do not fully introduce anything into your aquarium without consulting your pet store or researching reliable sites online as there will always be casualties! 

Prevent Diseases

Of course, you won’t prevent or combat as many things with a single step, but you should be able to determine if your guppy fish is experiencing diseases by observing them daily and ensuring they get their necessary needs. They only grow big and smelly if you treat them well, happy fish will make for happy people.

Overall Tank Maintenance

Think about a heater for the tank, especially if you’ve recently brought your guppy home from another location. In addition, you should check your water regularly and make sure it is clean. A heater will keep the temperature at a steady level, which can be very important for your guppy fish’s health. Make sure that you are providing them with a clean environment to live in. Your guppies will get sick if they don’t have enough oxygen or if their water quality is poor. If this happens, then they may not last very long in your tank.