Guppy Care Guide: How to Keep Healthy, Long-Lived Guppies

Guppies, with their dazzling colours and constant activity, are hard to ignore when browsing your local fish shop. It's no surprise that so many beginners choose a group for their first aquarium. However, success with this so-called beginner-friendly species is far from guaranteed.

So, what is it that always goes wrong? Why do so many people experience problems when keeping Poecilia reticulata, the scientific name for guppies, in their community tanks? Well, the truth is that modern fancy guppies are far removed from their wild ancestors, and some selectively bred strains can be considerably less robust as a result. However, with the right care and precautions, they can still be incredibly rewarding fish for both beginner and experienced aquarists.

All photos by Shutterstock unless otherwise stated

Guppy Fact File

Scientific name: Poecilia reticulata

Size: Females up to 5cm (2"), males typically remain smaller.

Origin: Native to Venezuela, Barbados, Trinidad, northern Brazil and the Guianas although it has been introduced elsewhere for mosquito control.

Habitat: They can be found in a wide range of habitat types including: rocky mountain streams, canals and drainage ditches, lakes, springs, floodplains and ponds. Their habitat can be clear water or turbid, filled with lush aquatic plants or barren habitats of sand and rocks, and can be flowing or stagnant. 

Minimum tank size: 60x30x30cm (24x12x12") for a group.

Water requirements: Prefer moderately hard to hard, alkaline water. Aim for stable conditions with the range of pH 7–8, and 9-20 dH. 

Temperature: 22-28°C (72-83°F).

Temperament: Peaceful towards other species, although males can be overzealous towards females. The long fins of many captive strains make them particularly vulnerable to fin-nipping species, so avoid keeping guppies with known fin-nippers.

Feeding: An unfussy omnivore, offer a variety of flakes, granules, live and frozen foods and ensure some greenery is included.

Availability & cost: Incredibly common and stocked in almost every store. Prices usually start at £2.50 but can be a lot more for desirable strains. 

Are guppies really beginner fish?

This seems like the most sensible place to start, because they're often included in "Top Tropical Fish for Beginners" lists. Unfortunately, it isn't really that simple, there are far too many variables to be able to state categorically whether they are, or are not, beginner fish. 

Wild guppy male - Photo by Alex Bell

If you were to get your hands on wild guppies, the likelihood is that they would certainly be hardy, robust fish capable of withstanding some minor beginner mistakes (once any infections brought in from the wild are dealt with). They are found across a huge array of habitat types and countries thanks to humans, and it stands to reason the water parameters and conditions vary considerably between these. 

However, the chance of seeing wild guppies offered for sale at your local shop is incredibly slim. The chance of a beginner picking one of these rather plain looking fish over the elaborate colours and fins of captive bred male guppies is even slimmer. And it is these fish that typically have more problems. 

Years of selective breeding, sometimes accompanied by poor breeding practices and excessive inbreeding, can leave some captive strains considerably less robust than their wild counterparts. From my time in the trade it was not uncommon to see cohorts of guppies struggle to adapt to life in the shop despite the water conditions being within the "optimal" range. 

They seem more prone to diseases, less adaptable to changes in water parameters, and in general harder to succeed with. That's not to say they're all like this, but it does mean we aquarists need to be a little more picky. 

Choosing the right guppies

Success with guppies often starts before you even buy a single fish. With so many guppies in the hobby, it is important that you pick the right ones for you. However, this isn't just about picking the colour strains you like the look of; choosing healthy fish is far more important than aesthetics alone.

Where you buy your guppies matters

Many of us will have a handful of stores within driving distance, as well as plenty of online retailers. There is an abundance of choice before you even leave the comfort of your home. We all know the pros and cons of buying fish online, and wherever possible seeing the fish in person is always the preferred option, and this is certainly the case with guppies as well. 

Photo by Alex Bell

Related article: Fishkeeping questions commonly asked in fish stores.

The next thing I would consider is how much time you have. Visiting several shops and comparing their guppies in person is a great place to start if you are able to. You'll then be able to spot the healthiest fish – more on this in a moment.

However, if this is not an option consider looking at reviews, phoning around, and potentially checking their social media. You'll quickly be able to gauge whether the shop has a good reputation, keeps its guppies correctly and provides good advice

Here are some examples of the questions I would be asking the shop staff:

• What is your quarantine procedure for new fish, specifically guppies?
• Do you always buy your guppies from one supplier? If not, do you mix them up in the same tanks or keep fish from different suppliers separately? 
• What water parameters do you keep your guppies in? 

A meaningful quarantine period gives a shop more opportunity to identify diseases before fish are offered for sale, although no quarantine period can guarantee that a fish is disease-free.

Likewise, mixing fish from different sources may introduce a pathogen to which fish from one source may be less resilient to. This isn't the end of the world, but a shop that purposefully keeps their guppies from different sources/batches separately is a good sign.

Finally, if they can explain the water parameters they maintain and how they keep them stable, that's a good sign that they understand the needs of their fish rather than simply keeping them in whatever water comes out of the tap.

Look beyond colour

It is very easy to walk through the shop and just pick the guppies with the boldest and brightest colours, or the longest, flashiest fins. However, it is important to look closer than that. By all means pick strains of guppies that you like the look of, but be prepared to walk away and wait to find the right ones if they don't look right.

When choosing your guppies you should assess the following:

• Body shape – look out for bent spines, overtly large abdomens (in males), or skinny fish
• Swimming behaviour – guppies should be active and alert. If any fish is sulking at the bottom on its own, or gasping in the corner, or swimming erratically, don't buy any from that tank. 
• Fins – Look out for severe nips and fin erosion. Also, watch out for fins that are draping down and hanging lower than the fish's body. It could be that the fin is just too big and heavy, but it could also be a fish that is no longer strong enough to hold it up. 
• Appetite – Ask to see the fish feeding. Guppies are always enthusiastic at feeding time and any fish not feeding, or spitting out their food, means you should walk away. 
• General signs of disease – You are likely already aware of some of the common symptoms of disease, including white spots, cloudy eyes, distended abdomens, pinecone scales, open wounds and ulcers. Again, if any fish is showing signs of disease do not buy any fish from that tank. 
• Dead fish – Even if the other fish look healthy, a dead fish or two should start alarm bells ringing. 

The most impressive fish isn't always the right choice 

While bold colours and elaborate ornaments can be associated with health and vigour in wild animals, this isn't necessarily the case with selectively bred guppies.

I'd always recommend buying the healthiest looking fish. The one that feeds well, is active, alert, interacting normally with its tank mates and is in good condition over the guppy with the best colouration. 

Related article: Picking your first tropical aquarium fish.

Look at the whole tank, not just the fish

Even if the guppy you like the look of looks great and shows no symptoms or signs of ill-health, you still must look at the rest of the tank. Check the overall cleanliness of the tank, and all tank mates. 

You should look for: 

• Dead or dying fish
• Fish gasping at the surface
• Cloudy water 
• Excessive build-up of waste
• All the above signs of ill health but in their tankmates 

Choosing female guppies

I've focused a lot on male guppies so far, mostly because they are the fish that people fall in love with when visiting stores. It isn't that the females are ugly, but they are not quite as elaborate as the males. Males often become overly attentive, for want of a better word, towards females which can have a negative impact on their health and wellbeing. Because of this, it is common for people to keep tanks of just males to remove this problem.

For those wanting to keep both, which we'll discuss in a moment, much of the above is also true with females, but there is usually a much more limited choice. A tank full of female guppies all sporting slightly different markings on the tail is usually the best you'll get, pictured above. Just because there's less to choose from it doesn't mean you should not be picky. Shop around until you find a healthy looking tank to pick from.

Females are often larger and more rotund, and their anal fin is rounded like a fan. Males are more streamlined, have brighter colours, and the anal fin is narrow and pointed (called a gonopodium).

Male top, female bottom

Should you keep male and female guppies together? 

From my experience, keeping both males and females together is less common in the UK than keeping all male groups, but that does not mean it is impossible. If you want to keep male and female guppies together you should ensure you have more females than males. This will spread out the males' attention across multiple females and prevent any one individual getting harassed constantly. 

Keeping at least two females to every male is the minimum I'd recommend, but three females would be even better. Maintaining large groups in a well decorated tank with plenty of cover can also help provide some relief for the females. 

But there is another problem with keeping males and females together: you are almost certainly going to get babies. 

Guppy breeding: what happens next

Guppy fry are almost inevitable if you keep female guppies. In fact, you don't even need a male!

Female guppies are able to store sperm after mating and use it to fertilise several subsequent batches of fry. When you buy a female guppy, there is a chance that, if she has shared a tank with males within the previous few months, she could still be carrying stored sperm or may already be pregnant.

This may sound brilliant initially – more fish for free! But it's actually a bit of a problem.

How many fry will a guppy produce?

Brood size varies with a female's age, size, diet, and condition, so it is impossible to know exactly how many fry you'll get from your pregnant female. The average brood size is usually somewhere around 20 to 40 fry so you can use this as a rough guide. Younger females often have much smaller broods initially. 

This means the young are born as free-swimming fry rather than spending their early development as exposed eggs, and a surprising number can survive in a well-established aquarium. Gestation is typically around four weeks, so a healthy female can potentially produce a new brood roughly every month. Then, once the babies are having babies, it can truly spiral out of control.

So, the problem isn't producing guppy fry; it is finding somewhere for them to go. 

Related article: How to breed livebearing fish.

What to do with all the babies?

The resulting offspring are unlikely to reliably reproduce the same patterns and colours as their parents. There is huge variety in the patterns and colours of guppies, each a result of years of meticulous selective breeding. In many general fish shops, females aren't sold as carefully matched breeding partners to males, so the chance of both parents belonging to the same established strain can be slim.

Without knowing the parents' lineage, it can be difficult to predict what your offspring will look like, and they are unlikely to reproduce the characteristics of a recognised pure strain reliably. This can make the offspring difficult to rehome. Hobbyists looking for a particular strain won't necessarily want mixed or unknown-lineage guppies, while many fish shops have little demand for large numbers of home-bred fish and may not be able to take them at all.

Never assume your local shop will take your surplus guppies – ask before you start breeding.

Don't want guppy fry?

The easiest option is usually to keep just males. Male-only groups can make a colourful and attractive display, and aggression is often manageable when the fish are kept in an appropriately sized group and aquarium.

Keeping only females can work, but carries some risk that they may already be pregnant or be carrying sperm. They are also the less colourful of the genders, which makes this option not the most popular. 

You should never rely on natural predation in the tank. Even alongside larger fish, some fry often find a way to survive to adulthood.

It might be tempting to use surplus guppy fry as food for larger predatory fish, but this is not an appropriate way to deal with unwanted offspring. PFK has previously contacted Defra about the legality of feeding live fish. While Defra confirmed that live feeding is not expressly prohibited, it also stated that causing unnecessary suffering to an animal under human control is an offence and that live feeding may constitute unnecessary suffering. Ultimately, whether a particular case constitutes an offence would be a matter for the courts.

Our advice is simple: don't do it. 

If you accidentally end up with some fry, rehome them responsibly. Ask around at local stores, join local fish clubs or auctions. Don't simply give them away to the first person who responds to an advert. Whoever takes them should have an appropriate aquarium and be able to care for them properly.

Finally, never release unwanted guppies into ponds, rivers or other waterways. Apart from being irresponsible, guppies are already established outside their native range in many parts of the world.

What if I want to become a guppy breeder? 

Anyone can end up with fry by accidentally mixing males and females. Selectively breeding a healthy, consistent strain is a much more intensive project. For many hobbyists who simply want to keep guppies, it isn't the aim. However, if this is something that interests you there is an article all about breeding the perfect guppies in our archive. 

For the more casual hobbyist breeder, it is usually best to attempt to track down males and females from the same strain. Some stores will be able to order pairs of known guppy strains, but they will come at a premium. Alternatively, you can source them from other breeders. The British Livebearer Association host auctions where you may be able to find established strains that aren't readily available in local fish shops.

Housing guppies correctly

So we've learnt about choosing the right guppies and how breeding them can be problematic, but how should we keep them to ensure they live long, healthy lives in your aquarium? 

Well, some of this will depend on whether you are keeping just males, or mixed sex groups, and whether you plan to breed them or want them as part of a community with other species. I'll do my best to cover all of the options where possible in the following section.

How big should a guppy tank be?

There isn't one universally appropriate tank size for guppies. The aquarium you need depends on how many fish you're keeping, their sex, and whether you're planning to breed them. However, a general rule applies here: footprint is more important than height, as it gives guppies more swimming space and more opportunities to seek refuge from each other.  

For a group of six to ten males I would be comfortable stocking them in a 54-litre (12 gal) 60x30x30cm (24x12x12") aquarium. This provides enough space for them to explore, sufficient numbers to spread out any male-male aggression, and an attractive display without looking crowded.

For a pair or trio being kept specifically for breeding, a 45x25x25cm (18x10x10") tank can work, if fry are removed and reared in a separate grow out tank.

For a mixed sex group in a long term community, one or two males and four females could work in the above 54-litre (12 gal) tank. However, careful population management would need to take place to prevent this becoming crowded, for example having a reliable plan for rehoming surplus fry. Ideally, for a mixed sex guppy community, I'd probably go a little larger to allow for more fry to grow up alongside the parents, and perhaps more importantly, a larger group of colourful adult males. 

Setting up the aquarium

 The essentials are the same as with any aquarium.

• A heater – guppies are tropical fish and need a stable temperature within their preferred range.
• A light – will help you grow live plants and improve visibility of your fish.
• A filter – to remove waste from the water and provide the biological filtration your aquarium needs.

We always recommend that the filter is matured by fishless cycling when setting up a new aquarium, but this process can be accelerated by utilising bacterial starter products or mature filter media. For a guppy tank, you don't want excessive flow, so choose a filter appropriate for the aquarium and avoid creating a strong current. Fancy guppies with long tails can struggle to swim against it.

Then you can choose décor that will suit your preferences, to some degree. There are still a few things to consider. 

• Add plenty of décor. Dense planting, wood, rocks and other structures give guppies somewhere to retreat to, which can actually encourage them to spend more time out in the open. It can also increase the survival rate of fry, as they can hide from the hungry mouths of adults more easily.
• Add surface cover. Guppies spend a lot of time towards the top of the aquarium and will appreciate the additional security provided by floating plants, for example.
• Avoid brightly coloured gravel. This is more for aesthetic reasons than welfare, but the fish should be the stars of the show, and rainbow gravel can compete with the guppies for attention. A neutral-coloured gravel or natural sand is a better choice. 

Live plants are particularly useful for guppies. They provide cover, help break up lines of sight between fish and offer excellent refuge for fry. Fast-growing or dense plants can also make a new aquarium feel more established and natural, and they don't have to be difficult to grow. There are plenty of great, easy-to-grow plants available, such as Anubias, Vallisneria, Java fern, and Cryptocoryne.

Related article: 5 easy and beautiful stem plants for your aquascape.

Water parameters

This is definitely a key part to having success with guppies long term. Guppies generally do better in hard, alkaline water than in soft, acidic conditions. For many, this is not an issue and suitably hard and alkaline water will just come out of your tap.

However, for those in soft water areas, like me, you'll need to add some extra minerals to keep your guppies healthy long term. GH is a measure of the dissolved calcium and magnesium in the water, while KH measures its carbonate and bicarbonate content (alkalinity) and therefore its ability to resist changes in pH. Some products will raise only the KH, some the GH, while others are full spectrum remineralising salts designed to add all of the minerals (including the trace elements) back into the water.

Related article: Understanding water hardness.

What you shouldn't do is just add some table salt; this is not the same thing! Table salt is primarily sodium chloride and doesn't provide the minerals needed to increase GH and KH.

As a general guide, aim for a pH of 7-8, 9-20 dGH, and a KH of 5-15. Don't chase specific numbers within these ranges as that can lead to unnecessary and potentially harmful fluctuations. Stability is often more important than trying to maintain a pH of exactly 7.2 or 7.5.

Photo by Alex Bell

While materials like ocean rock and coral sand contain calcium carbonate that can slowly dissolve, raising pH and hardness, relying on them to buffer an aquarium can make water chemistry less predictable. If your tap water is significantly softer or more acidic than the aquarium, each water change can then cause the parameters to fluctuate.

You should always be aiming to match the incoming water's parameters with what is already in the tank. 

As we mentioned earlier, guppies are tropical fish and need a heater to maintain a stable temperature. Some sources recommend a broad range of 20 to 28°C (68-82°F), but I'd bring that a little closer and set your heater at around 24-26°C (75-79°F).

Did you know?

Temperature may also influence sex ratios in guppy offspring, with some studies reporting a greater proportion of males at higher temperatures, although this is not something aquarists should rely on when managing breeding.

Feeding guppies

Feeding guppies is generally straightforward. They are adaptable, unfussy omnivores that will readily accept a wide range of foods. In the wild, they feed on zooplankton and insect larvae, along with algae and other organic matter.

To replicate this varied diet in the aquarium, offer a good-quality prepared food as the staple, including foods containing plant-based ingredients such as spirulina. A few times a week, you can also supplement this with small amounts of live or frozen foods. Daphnia and Cyclops are particularly good options because they are suitably small for guppies, while brine shrimp and bloodworms will also be readily accepted.

Feed small portions that your guppies can consume quickly, rather than adding more food than they need. Uneaten food can quickly contribute to declining water quality.

Choosing compatible tankmates

Don't choose tank mates based on temperament alone. A fish being peaceful doesn't necessarily make it a suitable companion for guppies. Look for species that are comfortable in the same water chemistry and temperature range, have compatible behaviour, and are appropriate for the size of aquarium.

This is why the commonly recommended neon and cardinal tetras aren't ideal choices for a guppy aquarium: their usual preferred conditions are softer and more acidic than those favoured by guppies. 

If you want a shoal of tetras, consider the x-ray tetra (Pristella maxillaris) instead. They are relatively hardy and well suited to harder water, and records suggest they can sometimes even be found in slightly brackish water in the wild.They are not known to be aggressive fin-nippers, but I would want to keep a group of at least eight x-ray tetras. 

For bottom dwellers, look for something peaceful that can also thrive in similar conditions to your guppies. Some of the hardier Corydoras are worth considering, particularly peppered corydoras (Hoplisoma paleatum) and bronze corydoras (Osteogaster aenea). Both are adaptable species that can cope with moderately hard water, making them more suitable companions for guppies than some of the softer-water Corydoras.

Remember, however, that bottom-feeding fish need specific care themselves and are not going to help "clean your tank". Buy them because you like the fish, not because you want to skip a water change. Corydoras are social fish and should be kept in appropriate groups, while their feeding needs should be met with suitable sinking foods rather than relying on leftovers from other fish.

Substrate is also important. Corydoras spend much of their time foraging through the bottom of the aquarium, so a soft, fine substrate such as sand is preferable. Sharp or abrasive gravel can damage their sensitive barbels and is best avoided. If you have chosen a coarse gravel substrate, it will be best to avoid corydoras.

Ultimately, the best tank mates are not simply fish that can tolerate the same conditions as guppies. They are fish that can genuinely thrive alongside them, without either species having to compromise its requirements.

Endler's guppy male

Other livebearers may seem like the most obvious choice, but there are drawbacks. Mollies, platies, and other livebearers can produce large numbers of young just like the guppies, and a mixed-sex livebearer community can quickly become overrun with fry. Guppies can also hybridise with Endler's livebearers and, less commonly, with mollies, which can create further complications if you want to maintain distinct species or strains.

Why guppies get sick

Despite your best efforts, one of your guppies may get sick. It happens, and it isn't always the fault of the fishkeeper. The first signs will often be the same behavioural changes you should look for when visiting a fish shop to buy your guppies in the first place: a fish that is lethargic, hiding, breathing unusually quickly, not eating, swimming abnormally or separating itself from the rest of the group.

If you spot something unusual, the first thing to do is check the water to see if something has changed. An ammonia or nitrite spike, a sudden change in pH, or a broken heater that has allowed the temperature to drop can all stress fish and make them more susceptible to disease. Don't assume that an illness is the problem until you've ruled out poor or unstable water quality.

It may also be that you have recently added a new fish. Even if it appeared healthy in the shop, it could have been carrying a pathogen without showing obvious symptoms. This is one reason why quarantining new fish before adding them to an established aquarium is such a useful precaution.

Treating a disease first requires you to have a reasonable idea of what is causing the problem. Bacterial infections, internal parasites, flukes and white spot are among the problems you may encounter with guppies, but many diseases can produce similar symptoms. A thin fish, for example, could be suffering from an internal parasite, but wasting can have several other causes too.

If you aren't sure what is wrong, take clear photographs or, even better, a short video of the affected fish and record your water parameters, recent changes to the aquarium, and any other symptoms you've noticed. An experienced fishkeeper or knowledgeable aquatic retailer may be able to help you narrow down the possibilities. Where the cause remains unclear, seek advice before medicating the aquarium.

Most importantly, don't panic. Finding a sick fish doesn't necessarily mean that your whole aquarium is going to be affected. Identify and correct any environmental problems first, observe the other fish carefully, and treat the underlying problem appropriately when needed.

Related article: Frequently asked questions on treating sick fish.

So, are guppies really beginner fish?

Yes – but with a few important caveats.

There is a reason they have remained so popular for generations. They are colourful, active, relatively small, and readily available. The problem is that not every guppy is equally robust, and the fish available in the hobby today can be considerably less forgiving than their reputation suggests.

For the beginner, the key is to avoid treating guppies as indestructible fish that can simply be dropped into any community aquarium. Choose healthy fish from a reputable source, make sure your water is suitable and stable, provide enough space and cover, and think carefully about whether you want to deal with the inevitable fry before mixing males and females.

Perhaps most importantly, don't compromise on the needs of your guppies simply because they are considered a beginner species. If your tap water is soft and acidic, another species may be a better choice. If you don't have the space to manage a growing population, keep males only. If a particular strain looks impressive but appears weak or unhealthy, walk away and find better fish.

Get those fundamentals right and guppies can be every bit as rewarding as their reputation suggests. Their popularity is not undeserved – they just deserve a little more care and consideration than the label "beginner fish" sometimes implies.

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