how to care for guppies

Many people keep guppies because they are hearty little fish with adventurous personalities. That being said, proper care is still essential if you expect them to have a normal, healthy lifespan.

Learning how to care for guppies is an excellent way to hone your skills with freshwater aquariums, and also begin learning more about saltwater tank care.

Overall, guppies are silvery colored, slim bodied fish with round tails. Males have larger, brighter colored tails, while females tend to have larger bodies at maturity. 

Both males and females swim quickly and will dart in all directions. Unlike other aquarium fish, guppies do not jump out of the water to hunt insects or for other discernible purposes.

Nevertheless, they do prepare themselves to jump out of the water, and will do so as often as possible.

Some researchers think they jump because they want to get to another body of water for the purpose of spreading out their population. 

As small as guppies, they pack a lot of personality and curiosity into small bodies. They are an enjoyable fish to keep at the home aquarist level and will quickly get to know you.

If you are interested in fish that are smart enough to train, or want an aquatic pet that will interact with you, guppies are an ideal choice.

Quick Intro to GUPPIES

Scientific NamePoecilia reticulata
Other Common NamesMillionfish, Rainbow Fish
Care LevelModerate

Author Note: Most aquarium keepers say guppies are easy to care for. I differ from this view because I have seen too many modern female guppies have problems delivering fry, and wind up dying as a result. 

As with bettas and several other species of pet aquarium fish, I feel over-breeding, irresponsible rearing methods, and over-emphasis on antibiotics have made guppies weaker across the generations.

This doesn’t affect just a female’s ability to give birth to fry, it also leads to frequent and often fatal immune system collapses, swimbladder problems, inability to thrive in deeper tanks, and other health problems. 

Originally, guppies came from brackish waters extending from Western Venezuela to the Southern Lesser Antilles. Today, they are found in many parts of the world and are considered an invasive species. 

While some guppies were most likely released by aquarists that no longer wanted them as pets, others were deliberately released in an effort to control mosquitoes.

Since guppies feed on mosquito larvae, some researchers thought this would be a good way to eliminate these pests.

Instead, the guppies quickly took over the habitat and now threaten many aquatic species that live in the same waters with them. 

Even though guppies can survive for a time in strictly fresh water, I have found the females definitely need at least some aquarium salt while they are pregnant.

Since female guppies are almost always pregnant once they reach maturity, this means there is always a need to provide brackish water. 

Author Note: As livebearers, guppies are similar to sword tail, mollies, and platies. Personality-wise, I’ve often found that female guppies are more similar to swordtails than they are mollies. 

Optimal Water Conditions For Guppies

Water Temperature65 – 83 degrees Fahrenheit
Water Flow RateMedium
pH7 – 8
Hardness9 – 19
Aquarium Salt RecommendationsYes
Tannin RecommendationsNo
Other Water Chemistry NeedsPrefer well oxygenated water.

Regarding hardness, guppies do best in hard water high in dissolved magnesium and calcium.

Keep the carbonate component only high enough to create some stability in the pH, or higher if the guppies show no sign of gill swelling or distress.

Tank Setup for GUPPIES

Minimum Tank Size5 gallon
Optimal Tank Size10 gallons
Optimal Tank ShapeShallow and wide
Recommended Filter TypeSponge or box filter
Extra Air Flow and and How to Provide It

Extra Air Flow and How to Provide It: Keep airstones near the surface. Set them so that the bubbles break water surface tension in a fairly brisk manner.

This will improve air exchange and improve oxygen levels in the water without making the water flow overly brisk.

To start, I recommend starting your guppy tank on the alkaline side, around pH 8.0, and then let it shift towards neutral over time as opposed to constantly adjusting towards alkaline.

If the changes happen slowly enough, the fish will adapt to it. 

Never let your guppy tank slide into an acidic pH. Unfortunately, the nitrifying cycle in the tank will always swing the water chemistry towards acidic. Once the pH reaches around 7.5, you can add pH up, but do so slowly.

Guppies are highly susceptible to carbonate poisoning, so I don’t recommend using materials that increase pH and carbonate (for buffering/pH stabilizing) at the same time. 

Insofar as testing, it is best to check pH, hardness, ammonia, nitrates, and nitrates weekly during the first year, and then twice a week after that.

You should also test for salinity before adding aquarium salt to the tank and after topping off. Keeping salt levels in the optimal range will help immensely, especially for female guppies.

Creating the Landscape for your GUPPIES

fancy guppy
fancy guppy in aquarium

In the wild, most guppies live in somewhat shallow water with a lot of plants to hide in. You may find them in ponds with dense plants as well as ditches that are overgrown with weeds. 

Best Plants

Any plant that produces a good mix of stems and leaves. Guppies need a lot of room to swim and dart right along with plenty of cover.

Top Tip: I recommend areas that are heavily planted with shorter, somewhat open structure plants, and then areas with taller plants that have stems that support the leaves.

Best Lighting

They do best with medium to bright lighting.

Best Decorations

Natural plants of varying sizes and shapes, soft toys made from aquarium tubing that give way easily.

Since guppies move rapidly in all directions, anything that confines them can be something they will bump into hard enough to injure themselves.

Decorations to Avoid for guppies

Avoid anything that can trap the fish such as airstone driven plastic toys that open and close. Even though guppies are small and fairly flexible, they can easily get trapped in toys that have holes to swim in and out of.

Avoid plastic toys and others that may have sharp seams that can damage the fish’s slime coat and gill coverings.

It is also best to avoid seashells or anything that will leach carbonate into the water. If you are going to use driftwood, make sure all the tannins have been leached out of it. 

Physiological Considerations

Maximum Size1 – 1 ½ inches
Rate of GrowthReach reproductive maturity in about 2 – 3 months.
Lifespan2 – 4 years.
TemperamentMostly peaceful (can be aggressive about food or mates)
Preferred Tank RegionUpper regions of the tank. May avoid going lower if the tank is too deep. (Other aquarists say they enjoy all areas)
Scale ThicknessFairly sturdy scales. Therefore you can use most antibiotics for freshwater fish.
Gill ConsiderationsGuppies can be susceptible to gill swelling and flukes. Must balance water flow for gill health and ease of swimming. They’re shallow water fish, and overbreeding has made them about as weak in this department as bettas.
Swimbladder ConsiderationsEven though guppies are not narrow-bodied or deep bellied, they do tend to have swim bladder problems. Keep them in shallow tanks to help with this, and feed green peas weekly.
Fin Shape ConsiderationsGuppies have compact, powerful fins that can help them jump several feet out of the water. As small as their fins seem, they make navigation and agility easy for guppies to achieve.

Society for guppies

Guppies will swim together in loose schools that break apart when the males chase fertile females. Males tend to be slightly more aggressive than females, although both can show the classic markings for their species. 

There are some fascinating studies that reveal some things about guppy psychology. Here are two things that you might be able to observe right in a home tank:

  • Females will choose a mate within 10 minutes of seeing a male for the first time. 
  • While male guppy intelligence is not based on body or brain size, there are marked differences in these ratios in female fish. Essentially, the larger a female fish is, the bigger her brain is. Larger brained female guppies can do more tricks and will learn faster. They will also choose mates with bigger and brighter tails.

Even though guppies are fairly peaceful species among themselves and with other creatures, males can be very annoying because they are always looking to mate.

Top Tip: Most people say have a 1 male to 2 female ratio in the tank. My personal recommendation from years of observation is 1 male to 5 females. 

Some people claim that 2 females to each male is sufficient to divide the stress of being chased in half. The problem comes in when the females are not fertile at the same time.

To add insult to injury, the optimally sized tank for guppies doesn’t give females much room to escape and hide.

If you are going to buy the usual half dozen of a species, go with 1 male guppy to 5 females. Since guppies put a fairly small bioload on the tank, you can easily fit 12 fish to a 10 gallon tank, which would give you 2 males to 10 females.

I do not recommend keeping an all-male tank because the males will become very aggressive among themselves and fight. An all-female tank is an option since the females rarely fight among themselves.

This also reduces fish loss due to females being unable to deliver fry. Unfortunately, if the females are already impregnated (females can store sperm for 2 or more cycles) then you may still lose them when they try to deliver the fry.

Male guppies and their endless efforts to mate can be a problem for other fish in the tank that look like female guppies.

It is not a good idea to house male guppies with juvenile or adult fish of other species that may have a similar shape to female guppies. 

As a case in point, I have personally witnessed male guppies trying to mate with female betta fish. If you are planning to keep a female betta, house her only with female guppies or other peaceful tank mates. 

Interestingly enough, some researchers think males attempting to mate with similar species in a natural setting contributes to the decline of native populations.

This occurs because the males of many species fertilize eggs only after they are released from the female’s body. 

Guppies are different because the male inserts his gonopodium (modified anal fin) into the females egg vent, and then releases sperm.

Guppy males have “claws” or barbs on the tip of their gonopodium that can damage the female’s vent, especially if the female does not want to mate. 

Unfortunately, when a male guppy successfully inserts his gonopodium into the vent of a fish from another species, it can do harm to the reproductive system.

A female guppy’s vent is designed for this activity. Other species may not be able to lay eggs or may have other problems releasing eggs if scar tissue develops.

Other than problems associated with male trying to mate with other species of fish in the tank, they are relatively peaceful creatures that will get along with fish that are about their same size.

Do not put guppies in with larger or more aggressive fish, as these fish will hunt and consume the smaller animals.

Managing Guppy Aggression


As with many other species of fish, aggressive guppies may flare their fins, nip at other fish, and chase them.

Where many other species of fish will display higher contrast or brighter body colors to give a warning of hostile intent, the irises of a guppy’s eyes will turn black. Most of the time, this display of aggression occurs over food.

Here are some ways to manage aggression in guppies:

  • Healthy guppies of both genders have a very intense interest in food. Regardless of the tank size, you can expect male and female guppies to guard areas where food is abundant. Even if the fish go to the surface to consume meals, pay attention to where extra bits land in the tank. Adjust the location of airstones or other the filter so that there is more even distribution of extra food. 
  • Try providing 2 or more small meals per day, but do not overfeed the tank. 
  • Add more females to increase the ratio between males and females. You may also need to partition males off so that each has his own space and females to mate with. 
  • See if other fish in the tank are causing stress. If the tank is overcrowded or other species in the tank are hostile, guppies may become more aggressive, even among themselves.

Gender, Breeding, and Reproductive Considerations for guppies


 As a general rule of thumb, the more popular a species of fish is with home aquarists, the more tendency there is to over breed or use rearing practices that shorten the time it takes to reach a marketable size.

Both problems will lead to fish that get sick more often and increase the risk the fish will produce healthy offspring.

Many people that could take part in breeding tropical fish, or even endangered ones quickly lose interest when they are unable to successfully raise fish from birth to maturity.

Unfortunately, many of these failures have to do with parent fish that simply aren’t genetically viable. 

When you reach a point where you want to try breeding guppies, start off with one or more sets certified for breeding.

This will ensure that you are starting off with fish that have the genetic and physical strength to produce healthy offspring.

From there, breeding guppies is actually very simple. Just put males and females together, and let nature take its course.

Once females start releasing live baby guppies, they will do so every 4 – 6 weeks. Even if there are no males in the tank, females may continue to release fry for several months until they use up any sperm stored away from previous matings.

Set the tank temperature to 78 degrees when you see the gravid spot (a black spot above or near the female’s vent) getting darker.

You may also want to do a 25% water change and add some aquarium salt (I found adding aquarium salt reduces the risk of the females not being able to release all the fry ready to be born).

Once a female is fertile, the male will chase the female and attempt to mate. Since it can take less than a second for a male to get close enough to the female and insert his gonopodium, don’t count on seeing the actual mating. 

If mating is successful, female fish will steadily become heavier in the belly. Watch carefully as the gravid spot gets larger and darker.

I’ve also noticed that female guppies get a little bit quieter and may spend more time hiding just before they release fry. 

Even though guppies are livebearers, they will eat fry almost as soon as they are released into the water, it is best to isolate a female that is about to give birth in a breeder tank.

Be sure to have plenty of aquarium grass and ground cover in the tank so the fry can hide, and divide the tank into 2 partitions.

When guppy fry emerge, they will look like tiny worms (under ¼ inch long) folded in half. As they exit the female’s vent, they will unfold and quickly swim for cover.

Unfortunately, if the female is watching closely, she may consume them as quickly as they are born. 

Female guppies will release 20 or more fry over the course of a few hours. According to researchers, this number will be smaller if the parents are larger brained fish.

If you spot 10 or so making it into safe areas of the tank, consider yourself lucky and partition the female off to the other half of the tank. 

Let the female stay in that partition for about 5 days, and then return her to the main tank. This will eliminate the chance of her being attacked by other guppies or other species of fish while she is releasing fry.

In addition, no matter how many hiding places there are, the constrained area can make it impossible for female guppies to find peace and quiet while they are recovering. 

It is very important to realize that modern female guppies often wind up with fry that do not make it outside. If fry get stuck, they will die in the female’s body, cause an infection, and ultimately lead to the female’s death. 

If all goes well, the other half of the partition will show signs of life almost immediately. Newborn guppies are capable of eating food as soon as they are born. Feed them crushed flakes or baby brine shrimp.

Author Note: As a point of note, I always make sure baby brine shrimp are dead before feeding them to fry. Sadly, I have seen perfectly healthy fry attacked by baby brine shrimp and die as a result.

Since guppies are extremely prolific, I don’t recommend trying to raise them from fry unless you have fish certified for breeding, a lot of room for new tanks and a viable venue to sell through.

Your best option may be to simply allow female guppies to consume the fry, as this will provide extra nutrition during the recovery stage.

Nutritional Needs

Blue Moscow Guppy (Poecilia reticulata var. “Blue Moscow”)

In a natural habitat, guppies usually dine on zooplankton and small insects. They are also well known for consuming mosquito larvae.

As in an aquarium setting, guppies will either go to the surface to consume food floating there, or pick at bits of food that may be resting on other objects and the substrate.

Best Sustenance Food TypeHikari brand Fancy Guppy Pellets, or Micro Pellets for tropical fish. As with other small fish, guppies can easily choke to death on flake food that gets stuck in their throat. Pellets reduce this risk and also foul the water less.
Additional Food for Optimal HealthAlgae, insect larvae
Special Foods and Considerations for Best Color and GrowthBrine shrimp
When and How Often to Feed Fish Based on Life CycleGuppies of all ages and genders do best when you feed them small meals 2- 3 times a day. You may want to increase this to 4 times a day for fry; however, you will need to watch carefully to avoid ammonia surges and pH swings.

Finnicky Fish Management

Perhaps more so than other species of fish, I noticed that guppies are more inclined to stop eating because of water chemistry problems than other fish.

In particular, females may stop eating, or eat poorly if there is no aquarium salt in the tank.

Here are some other issues that may lead to finnicky eating habits in guppies:

Females may also stop eating a day or so before they release fry.

They may also go off and hide and even refrain from coming up to say hello to you. If you are planning to raise fry, this would be the time to move the female guppy to a breeding tank.

She won’t necessarily start eating, but it will give her some peace and quiet.

Another fish in the tank is acting aggressively towards them. Remember, if a guppy’s eyes turn black, it is a sign of aggression that is usually about food guarding.

If the other guppy isn’t eating or stops eating, it might be best to isolate the aggressive fish as it will simply go on to intimidate other fish in the tank.

Incorrect water chemistry – anything from acidic pH to high carbonate levels and ammonia surges can cause guppies to stop eating. If the whole school stops eating, this should be the first thing you look at.

Common Diseases and How to Avoid and Treat Them


Aside from carbonate poisoning, guppies are most susceptible to cottonmouth disease (also known as columnaris and guppy disease even though other species develop it as well).

They’re also prone to swimbladder disease (both bacterial and environment related), velvet, gill flukes, and tail rot.

If you notice guppies struggling to go from the bottom of the tank to the top, rolling in place, or their bellies are distended, they may have either environmental swimbladder disease. 

Start off by giving the guppies thawed peas as this will help push excess air out and help the fish regain its ability to regulate its position in the tank.

Reducing water depth by half will also help for both kinds of swimbladder disease. If the peas don’t help within an hour or two of feeding, it is best to start treatment for the bacterial form of swimbladder disease.

It should be noted that the way swimbladder disease affects swimming is very different from the 

 way a fish hangs nose up and gulping at the surface before rolling and swimming erratically through the tank as it dies.

How to Avoid Species-Specific Diseases

Most guppies get sick when their immune systems collapse. This, in turn, is often caused by environmental stress including poor water chemistry conditions and not enough places to hide.

As with most other tank inhabitants, water chemistry is key to keeping guppies healthy. Together with that, using chemical water chemistry adjusters instead of partial or complete water changes is less stressful to the fish. 

Best Antibiotics

I recommend using API brand antibiotics for guppy diseases. If other species of fish or creatures are in the tank, make sure the medications are safe to use with them. 

Cotton mouth and tail rot will usually respond to Erythromycin combined with Methylene Blue.

If that course of treatment fails to show results within 2 doses, do a 50% or more water change, filter with activated carbon for 12 hours, and switch to a Furan based product.

Always follow up a successful treatment with a partial water change plus carbon to remove the prior antibiotic, and then treat using API’s General Cure for any hidden velvet infections.

Treatments to Avoid

I don’t recommend “natural products” that do not use conventional antibiotics. Even though I have tried them several times, I have yet to see them act, let alone work quickly enough to manage a rapidly moving infection.

In many cases, once a fish shows signs of a bacterial or fungal infection, it can cover the body in as little as 24 hours. Conventional antibiotics offer the fastest route to recovery.

Food Recommendations When Sick

Medicated flakes to manage internal bacterial or parasitic infections. Even if the fish isn’t showing symptoms of these diseases, they may still crop up during treatment for other infections.

Hospital Tank or Isolation Within the Community Tank Specifics

For guppies, I recommend isolating sick fish and also treating the water in the main tank.

Guppies, like many other species of fish, will pick at and harass a sick fish. Isolation gives fish showing signs of illness a chance to recover.

Treating the water in the community tank can head off infection outbreaks in other fish that may be coming down with the same, or a different disease. 

Some Fascinating Facts About Guppies

Guppies are a unique, fun species that have a lot of unique characteristics – and history – that truly make them fascinating!

  1. Guppies are remarkably nosy creatures that need mental stimulation. You can teach them to swim through hoops much as you would bettas. Since they are agile swimmers, making an obstacle course of airline tubing will keep them busy and entertained. Just be sure to use soft live plants such as aponogetons around the hoops so they can hide and dart without getting hurt.
  2. If guppies consistently have environmental swimbladder problems, try releasing the food underwater instead of simply broadcasting it on top. This will help prevent guppies from taking in air while they are eating. Just make sure the fish are comfortable with consuming food in different regions of the tank. Some may adapt while others won’t. If you have fish that insist on feeding at the surface, make sure the others have eaten before putting food on the water surface.
  3. Broadcast food to different areas of the tank during each feeding to help curb food aggression at mealtime. Aggression may still happen later on, but wider dispersal increases the chance that each fish gets enough to eat. I don’t recommend using feeding rings or any other method that reduces food dispersal when feeding guppies.
  4. There are almost 300 different types of guppies that can be found in the Amazon, Brazil, Guyana, Trinidad, Tobago, Venezuela, and around Barbados. Who knew?
  5. Guppies are liverbearer fish, not egg layers. That’s pretty unusual in most of our minds, but livebearers are actually fairly common among fish. They’re just not the most common.
  6. Guppies are known commonly by two different names. Guppies and rainbowfish. Why? Because they of being named for Mr. Guppy as mentioned above and because of the wide array of colors these little guys come in.
  7. The name “guppy” is a namesake for Robert John Lechmere Guppy. He’s the researcher and geologist (with no formal scientific training!) who discovered these awesome little fish in 1866 in Trinidad.
  8. The guppy wasn’t so popular in the beginning. Before Robert Guppy found them, they technically were discovered by somebody else – W. C. H. Peters – who discovered them and decided they weren’t worth looking into.
  9. Guppies have been used to help doctors fight malaria. What?! These little fish have intentionally been set free in the waterways of Asia to help fight the spread of the deadly disease. In 2014, this anti-malaria “guppy movement” because in southern India and has been going strong ever since, thanks to the fish noshing on all those mosquito larvae that carry the deadly disease.

Where to Buy Guppies

For some time, guppies have been popular with both scientific researchers and home aquarists alike. Their capacity for rapid genetic change and relatively small size make them easy to care for and observe.

If you are comfortable with your current aquarium keeping skills and looking to move into the moderate level, guppies are an ideal choice.

While you can find guppies at most pet stores that sell aquatic pets, our preference is Amazon for convenience.

Here’s our top recommendation:


About The Author

1 thought on “How to Care for Guppies: A Complete Fact Sheet, Breeding, Behavior, and Care Guide”

  1. Great article, a lot of useful notes and specs as well. Been keeping goldfish indoor and outdoor for years. Just started a guppy tank so I can transition them to brackish and use that experience to start a full sea tank.

    Thank you, very helpful.

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