7 Reasons Your Guppy Is Dying & 5 Common Symptoms

Guppies are popular for a reason. They add a colorful serenity to any tank, and this makes them a popular addition to tanks for beginner and veteran aquarists alike. While they don’t normally require a lot of maintenance, there are definitely some things that you need to know if you want your guppies to thrive.

In this article, we’ll tell you the most important requirements for your guppy tank, red flags to watch for regarding their health, and we’ll finish it off with some best practices that can help to ensure that your guppies lead long, happy lives – let’s start it off with a ‘health’ checklist, and we’ll move on from there!

Why Is My Guppy Dying?

When you are housing guppies in your tank, there are a number of factors to consider in order to ensure that your fish are happy and healthy. Use the items below like a ‘health check’ list to get to the root of the health issues affecting your guppies.    

Ammonia, Nitrite, and Nitrate levels

Guppies are very sensitive to ammonia, nitrite, and nitrate level spikes, as these can compromise their immune systems and quickly kill them. Check your water, and you should see that Nitrates are less than 40 ppm, while ammonia and nitrite should both be at 0 ppm. If this is not the case, try a 25% water change to see if you can quickly balance the water to healthy levels.  

Low pH levels

Guppies do best at pH levels of 7 to 7.8, and anything below 7 starts making the water too acidic for their health. Try to always target a range between 7 and 7.8 for best results and consider adding crushed coral into their tank. This is one of the safest ways to help you to manage their pH level, especially if you need to fix the levels quickly.


Your guppies are tropical fish, and as such, they are going to be best suited for a temperature range of 72 to 82 degrees Fahrenheit. While these hardy fish can survive at temperatures above or below this, it has a cumulative effect on their health and can cause them eventually to sicken and die. Keeping your tank in this temperature range will help them to stay happy and healthy.

Tank Mate Aggression

Another good idea when determining why your guppies are dying is to take an inventory of their tank mates. As a general rule, any fish that have long, trailing fins may view guppies as their rivals and may attack them, with gouramis and bettas being a prime example of this.

Doublecheck the tank mates online to ensure that they can live peacefully with your guppies, or if changing mates is not an option, then consider adding extra hiding spaces to help give your guppies a better chance to get away.


The best defense against disease is to be proactive, so before you add new guppies to a tank, it’s a good idea to isolate them and medicate them before introducing them into their new environment. This is a good habit to get into, as many suppliers breed their fish in overcrowded tanks, and your fish may have been exposed to poor conditions.

Treating them first helps to ensure a clean slate getting started and protects all of the fish in your tank.

Acclimation Issues

If your guppies are dying quickly after introduction to their new tank, then you are looking at acclimation issues. If you are floating the bag in the water for 30 minutes prior to introduction, then this rules out a temperature issue, so you should check the pH of the water in the tank and the bag next.

If the difference is more than .2, you should start adding water from your tank very slowly into the bag until it is at about 75% tank water and 25% the water you brought them in. At this point, it should be safe to move them to the new tank.

Females May be Stressed

You need to have a 2 to 1 ratio of female to male guppies in your tank. If there are too few females, then males with breeding on their minds will chase them to exhaustion. By keeping a 2 to 1 balance then it gives females a chance to get away instead of spending the entire day fleeing the persistent males.

How To Know If Your Guppy is Dying

It takes a little practice to be able to spot a sick guppy – until you know what to look for. To that effect, we’ve compiled some telltale signs so that you can watch for, which will let you know that there is trouble afoot and that your guppies need your help. Let’s take a look at some definite signs of a sick guppy.

Lack of Appetite

One of the first signs that something is amiss is a lack of appetite. Ideally, you are feeding your guppies fish food and the occasional vegetables twice a day, and there should not be leftover food pooled in the tank. If there is, it might be an indicator that your guppies have ich, or it is possible that you are overfeeding them.


Your guppies are color-coded, in a way, when it comes to their health. When normally bright guppies seem to lose their shine and start looking dull, then you might have some sick guppies in your tank. Discoloration generally indicates sickness or stress, and it’s definitely something that you need to watch for.

Swollen Body

If one or more of your guppies looks a bit swollen, take a closer to look to see if they look a little scabby as well. If so, then your guppy may have dropsy, which is a bacterial infection that can kill your fish. While it is not contagious, change the water anyway – it’s conducive to bacterial growth right now – and you should isolate and treat the infected guppy.


White spots on the body are bad news, as they mean that one or more of your guppies has ich. ‘Ich’ is short for Ichthyicphthirius Multifilis, and it is a nasty parasite, and it is very contagious. You’ll need to immediately isolate the infected fish for treatment, and you’ll need medicine from your supplier to treat the tank.  

‘Bleeding’ Gills

If a close look at your guppy reveals that its gills seem to be bleeding, then this indicates a condition called ‘gill flukes’. Affected guppies may also appear as if they are having difficulty breathing, so this is a very easy condition to spot. You’ll need to go to your supplier for a medicine such as Praziquantel so that you can begin treatment right away.

How To Stop Your Guppy From Dying

When keeping guppies, there are some ‘best practices’ that you should observe and develop into habits if you want to keep your casualties at a minimum. Below you will find some good rules and practices to help you in cultivating a healthy guppy environment.

Cycle Water Before Introduction to Tank

Get in the habit of cycling your tank before introducing any new fish. While it’s a slow process (proper cycling takes about 2 weeks), it is very important, as guppies are extremely sensitive to changes in ammonia, nitrite, and nitrate levels. By planning in advance, you can ensure that your guppies are introduced safely into a pristine new environment for the best shot at a new life.

Regular Monitoring and Changing of Water

You should test your water frequently if you want to ensure that the pH, ammonia, nitrite, and nitrate levels are ideal. A good practice to get into as well is a weekly or bi-weekly change of 25% of the water. This helps keep toxins at a minimum and a better overall water quality for your fish.

Avoid Overcrowding Your Tank

A hard and fast rule for guppies is 2 gallons of water for every guppy. If you don’t follow this, then you’ll have overcrowding, along with extra waste to deal with, and some guppies may even suffocate due to a lack of oxygen. Make sure not to keep more than 5 guppies per 10 gallons, or you will definitely see fatalities.

Consider Their Diet

Guppies need a varied diet, so just having fish food is not going to be ideal. You should make sure that your guppies are occasionally getting live food, such as brine shrimp, and start adding the occasional fresh vegetables to their diet.

Adding veggies such as chopped-up peas and lettuce can keep them happy and give them an appreciable health boost, so make sure that your guppies are getting a diverse and healthy diet.

Ensure Tank Mates Are Compatible

Always double-check before adding a new tank mate in with your guppies. Even if they tell you at the store that the fish are compatible, double-check on your phone to make absolutely sure. Introducing an aggressive species into the tank can quickly decimate your guppy population, so it never hurts to get a second opinion before bringing a potential predator home.

Isolate Sick Guppies Immediately

You should maintain an isolation tank in case of emergencies so that the moment that you spot a sick fish, you can separate them and treat them separately while you also fortify and medicate your primary tank. A number of diseases are very contagious, and if you don’t move fast, the results can be brutal.

By isolating any sick fish right away, you’ll have a better chance at protecting all of your fish.   

Maintain Temperature Religiously

Fish are very sensitive to temperature levels, and just having a water heater doesn’t necessarily mean that everything is going to be okay. Be careful about the placement of your tank in order to ensure that there aren’t any environmental variables that might alter the water temperature in your absence.

Central heating and air vents, for instance, can make a big difference, and a tank close to the window means that you will get sunlight for various periods of the day… be careful with these, as they can make a difference!  

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Why Are My Male Guppies Dying?

Check your pH levels, followed by ammonia, nitrite, and nitrate levels. The widest comfortable range is 6.8 to 7.8, though 7 to 7.8 is ideal. Ammonia should be 0, nitrites at 0, and nitrates at less than 40 ppm. If this is not the case, do a 25% water change to help balance the levels.

Why Are My Female Guppies Dying?

When only female guppies are dying, there may be too many males in the tank. Ensure that you are keeping a 2 to 1 ratio of females to males so that male guppies who are looking to breed have more than one target to harass.

Some Final Words on Keeping You Guppies Happy

Guppies are pretty easy to maintain once you’ve gotten used to them. Just be sure to get into the habit of a 25% water change every 1 to 2 weeks, and this will really go a long way to keeping your water quality optimal.

Don’t forget to vary their diet. Before introducing new guppies, it’s a good idea to cycle their tank and isolate and treat the newcomers for disease before introducing them to their new environment. Beyond this, just be sure that they have a healthy, varied diet which includes occasional live food and vegetables and regularly check their water.

Take advantage of the tips which we have shared with you today, and before you know it, your guppies will be doing just fine!