Guppy Care on a Budget: Practical Tips for Affordable and Sustainable Aquarium Keeping

Guppy fish (lat. Poecilia reticulata) is a renowned tank fish. Even people who are not into aquarium husbandry know about this fish, not to mention aquarists. Each of them has surely had a guppy fish in a tank even just once. Some aquarists started their hobby from buying a couple of fish and even now they have some splendid selective breeding species. To answer all the questions about this fish we’d have to write a book, but we’ll try to discuss the most common ones here, in this article.

Natural habitat

The guppy fish, scientifically known as Poecilia reticulata, belongs to the family Poeciliidae. The family Poeciliidae is a diverse group of small freshwater fish commonly referred to as livebearers. It includes several other popular aquarium fish species, such as mollies, swordtails, and platies.

Guppy got its name in the name of English priest and scientist Robert John Lechmere Guppy, who in 1886 made a report to Royal Society, in which he told about the fish that spawns juveniles instead of eggs.

Are guppies tropical fish? Yes, Poecilia reticulata habitat is in freshwater and brackish water basins of Venezuela, Guiana, to the North of Amazon river, on the North of Brazil, Barbados islands and Trinidad. As a rule, the fish dwells in clean flowing water, but they also like brackish nearshore waters, but not salty seawater. Feeds on worms, larvae, bloodworm and various small insects. Due to this peculiarity the fish was acclimatized in all continents (guppy was brought to warm water basins all over the world to fight with larvae of malarial mosquito).

Guppies are known for their ability to adapt to different environmental conditions, which has contributed to their widespread distribution in the wild. They can be found in both clear and murky waters, ranging from densely vegetated areas to open water.

The natural habitat of guppies often consists of dense vegetation, including aquatic plants, submerged roots, and floating vegetation. These plants provide hiding places and shelter for the guppies, as well as serve as a source of food.

Water temperature in their native habitats can vary, but guppies are typically found in tropical or subtropical regions where temperatures range from 72°F to 82°F (22°C to 28°C). They can tolerate a wide pH range of water, but they generally prefer slightly acidic to neutral conditions with a pH level between 6.8 and 7.8.

In the wild males are more brightly colored than the females, though their colors is a far cry from those tank species obtained after selective breeding.

Description

Is a small sized fish with an elongated body with a slightly elongated abdomen. Guppies have various fin types and sizes. Males typically have larger, more elaborate fins compared to females. The dorsal fin, which runs along the back, can be long and flowing in males. The caudal fin (tail fin) can be fan-shaped, rounded, or even lyre-shaped, depending on the strain. The anal fin, ventral fins, and pectoral fins are also present and may have varying degrees of coloration and finnage.

Anal fin of male was modified into a reproductive organ – gonopodium. It is elongated and curved, which distinguishes male guppies from females. The female has a bit enlarged abdomen and you can see eggs in its anal region. Her fins are always proportionally smaller than that of the male. Most females from natural habitat have gray scales with pronounced diamond shaped pattern, which gave the name to the strain: reticulum (in Latin it means reticle, net).

Intraspecific variety of the fish colors, ability to breed fast and easily, allowed breeders to create unbelievable diversity of breeds with all possible types of patterns and color combinations. Guppies exhibit a wide range of colors and patterns, and their coloration can vary significantly between different strains and varieties. Common colors include red, orange, yellow, blue, green, purple, and black. Some guppies have a single solid color, while others have intricate patterns, spots, or stripes. Nowadays, it’s quite difficult to classify guppy, since as a result of numerous hybridization each year we get more and more new breeds.

Main parameter used for classification is the color of its body (mainly it’s male coloring), then comes the size, shape and color of its fins.

How long do guppies live?

Guppy fish lifespan is about 2 years in average. Provided with good tank conditions the fish can live up to 3 years in a tank. Some guppies have been known to live up to 5 years or more in exceptional cases. What we should mention, is that its lifespan reduces as the tank water temperature rises, due to the growth of metabolism processes rate. Providing a well-maintained aquarium environment, a balanced diet, and regular monitoring of their health can help maximize the lifespan of guppies.

How fast do guppies grow?

Provided with good tank conditions it grows very fast. Males become reproductive at the age of 2 months and females when being 3 months old. On average, guppies reach their full size within 3 to 4 months, but their growth can continue at a slower rate throughout their lifespan.

During the first few weeks of their lives, guppy fry (baby guppies) experience rapid growth. They grow quickly and can double or even triple their size within a matter of weeks. The growth rate slows down as they mature.

The growth rate of guppies can also be influenced by factors such as the quality and quantity of their food, water temperature, and the size of their environment. Providing a nutritious diet and maintaining optimal water conditions can promote healthy growth in guppies.

It’s important to note that male and female guppies can have different growth rates and sizes. Male guppies tend to be smaller than females and may mature at a slightly slower rate. Additionally, the growth rate can vary among different guppy strains and varieties, as some are bred for specific traits such as larger size or longer fins.

How big do guppies get?

Males are typically 1.5–3.5 cm (0.6–1.4 in) long, while females are 3–6 cm (1.2–2.4 in) long. The male body is elongated, thin and a bit flattened from sides. The female also has elongated body, but its back side is more flattened from sides. Males are much brighter colored and they also have gorgeous tails and fins, while females have rather pale coloring and short fins.

CharacteristicDescription
Scientific NamePoecilia reticulata
FamilyPoeciliidae
Native HabitatFreshwater streams, rivers, ponds, marshes (South America)
SizeMales: 1.5 to 2.4 inches (3.8 to 6 cm)
Females: 2 to 2.4 inches (5 to 6 cm)
Lifespan2 to 3 years (can vary based on care and environment)
Sexual DimorphismMales are smaller, more colorful, and have elongated fins
ColorationWide variety of colors and patterns
ReproductionLivebearers, females give birth to live young
DietOmnivorous, feeding on small insects, algae, and fish food
Water Temperature72°F to 82°F (22°C to 28°C)
Preferred pH Range6.8 to 7.8
BehaviorActive, social, and relatively peaceful
CompatibilityGenerally compatible with other peaceful fish species
HardinessHighly adaptable and can tolerate a range of water conditions

Difficulties in keeping

It’s an excellent fish both for beginners and professionals. It is small, active, nice, it breeds easily, not demanding as for the diet and keeping and we can continue this list on and on. The fish is not demanding, but it gets its maximum beauty only at favorable tank conditions.

However, we’d like to warn the beginners against buying bright fish types obtained after selective breeding. How to define such a fish? If all fishes in a tank are of one color, males have long and uniformly colored fins, then these are demanding guppy fishes.

If both males and females vary and they are differently colored, then these are the fishes exactly for the beginner aquarist. The thing is that guppy fish become very beautiful after selective breeding, but at the same time they become rather demanding and loose all their initial advantages.

Fancy guppy have low immunity and require special care. Therefore, if you decided to try yourself in aquarium husbandry, it’s better to get the simplest multicolored guppy fishes.

They will delight your eye as good as any selective breeding species, but they’ll live much longer and cause less problems. At that professional aquarists can get these demanding hybrids, though they should be carefully sorted and even more carefully bred and taken care of.

Care and keeping in a tank

Tank Size

The recommended tank size for guppies depends on various factors, including the number of fish, their size, and the desired level of activity and comfort. Small, but excessively active fish requires a small sized tank. The one of 10 gallons (38 liters) capacity will perfectly do for small group of guppies (around 2 to 4). However, providing them with sufficient space is essential for their well-being and overall health.

If you plan to keep a larger number of guppies or want to create a community tank with other fish species, it’s recommended to go for a larger aquarium. A 20 to 30-gallon (76 to 114 liters) tank or more would be appropriate to accommodate the additional fish and ensure compatibility among different species.

It’s important to consider the length and width of the tank, rather than just the volume. Guppies are active swimmers, so a tank with a length of at least 24 inches (61 cm) or more will provide them with enough horizontal swimming space. Additionally, having some vertical space with a tank height of 12 inches (30 cm) or more will allow the guppies to explore different levels of the aquarium.

When choosing a tank, you should take into account their high fertility. Number of the females in the tank has to be 2-3 times larger, than that of the male. Otherwise, the females will be stressed all the time due to the male fish haunting them. It is acceptable to keep only male in the tank, if you don’t need any offspring.

It’s worth mentioning that these recommendations are general guidelines, and the specific tank size can vary based on individual circumstances and the number of fish you plan to keep.

Water temperature

Though tank water temperature range for keeping guppy is quite wide (allowable range is 73–82°F (+23—28°C), the fish survives in the range from +14°C to +33°C), you should keep the temperature stable 72–79°F (22 – 26 °C). At low temperatures fishes grow larger, live for about 3—3.5 years, but at that they can easily get ill. Gestation period of female species gets longer and the juveniles are born rather large.

If tank water temperature is lower than 65°F (+18°C) the eggs development can stop at all and fish reproductive function is at rest. At high temperatures lifespan is about a year or less, they don’t grow large. Gestation period of the female becomes shorter and the juveniles are born small sized.

When keeping the fish at the lower temperature range 86-91°F (+30—33°C) “self-castration” of the fish is possible due to loss of activity and ability to spermatozoon fertilization.

Water Parameters

Maintaining proper water parameters is crucial for the health and well-being of guppies. Here are the recommended water parameters for guppy fish:

  1. pH Level: Guppies prefer a slightly acidic to neutral pH range. The recommended pH range for guppies is typically between 6.8 and 7.8, but it’s better to be 7.0. It’s important to monitor and maintain a stable pH level within this range to prevent stress or health issues.
  2. Water Hardness: Guppy fish adapt better to hard water and they stand brackish water quite well. Guppies are adaptable to a wide range of water hardness levels, but they generally prefer moderately hard water. Aim for a water hardness level between 8 and 12 dKH (carbonate hardness) or 120 to 180 ppm (parts per million) for the general well-being of your guppies.
  3. Ammonia and Nitrite: Ammonia and nitrite are toxic to fish, including guppies. It’s crucial to keep ammonia and nitrite levels at zero. Regular water testing and proper biological filtration are essential to maintain a healthy nitrogen cycle in the aquarium. Performing partial water changes and avoiding overfeeding can help prevent ammonia and nitrite buildup.
  4. Nitrate: Nitrate is the end product of the nitrogen cycle and is less harmful than ammonia and nitrite. However, high nitrate levels can still be detrimental to fish health. Aim to keep nitrate levels below 40 ppm through regular water changes, proper filtration, and the use of live plants to assist in nitrate removal.

Remember to use a reliable water testing kit to monitor the water parameters regularly. Conducting regular partial water changes (about 25% every 1-2 weeks) can help maintain stable water conditions and reduce the accumulation of toxins. We should also mention, that abrupt change of tank water temperature and chemical content (pH mainly) may become fatal to guppy fish adapt as well as keeping them in a tank with old water (without water renew) for a long time, which decreases their persistence to diseases.

Substrate

Here are some common substrate options for guppy fish tanks:

  1. Gravel: Gravel is a popular and widely used substrate for guppy tanks. It comes in various sizes, colors, and textures, allowing you to choose the one that suits your aquarium design. Gravel provides a natural appearance and allows for good water circulation. It also offers a surface for beneficial bacteria to colonize and assist in the biological filtration process. Dark colored small grained gravel is a good bottom substrate for the tank. This kind of substrate will only lay emphasis on the beauty and bright colored patterns.
  2. Sand: Sand is another common substrate choice for guppy tanks. It provides a smooth and natural-looking bottom and is gentle on the fish’s delicate fins. Sand is particularly suitable if you plan to keep bottom-dwelling fish species or if you want to create a more natural or planted tank environment. However, it’s important to ensure that the sand is fine-grained and doesn’t have sharp edges that could harm the guppies.
  3. Bare Bottom: Some aquarists opt for a bare-bottom tank, which means having no substrate at all. A bare-bottom tank has the advantage of easy maintenance and cleaning. Waste and debris can be easily siphoned out, reducing the chances of water quality issues. However, a bare-bottom tank may lack natural aesthetics and can be less beneficial for beneficial bacterial colonization.
  4. Soils: If you plan to keep live plants in your guppy tank, you might consider using a plant-specific substrate – soil. These substrates are typically enriched with nutrients and designed to provide a suitable environment for plant growth. Plant-specific substrates can promote healthy plant development and root anchoring, contributing to an aesthetically pleasing and thriving planted tank.

Decor

It’s not a good idea to put plants with large and coarse leaves into a tank. It’s better to put some tank plants with small leaves without sharp edges, that can harm the fins and tails. Adding live aquatic plants to the tank not only creates a natural and visually pleasing environment but also provides additional benefits. Live plants help maintain water quality by absorbing nitrates, provide hiding places for guppies, and contribute to oxygenation. Some suitable plant species for guppy tanks include Java moss, Anubias, Vallisneria, Amazon sword, and Java fern.

For the same reason, it’s not worth putting some rock shelters or other sharp edged objects like snags, stones etc. into the tank with fishes. Rocks and driftwood can be used to create caves, crevices, and hiding spots for guppies. They also add a natural look to the aquarium. Ensure that any rocks or driftwood you use are aquarium-safe and do not leach harmful substances into the water. Smooth snags and stones will make the tank look natural.

Filtration

It’s desirable to use a water filter (internal one will be quite enough), though if you have an external one, this will do as well. But it’s better to close its apertures with additional fine mesh, because a powerful filter can not only suck the juveniles inside it, but the adult fish, too.

We can’t call guppy a schooling fish, but there is almost no point in keeping just one fish couple. Since it’s a small sized fish, you will not notice a little number of them in a tank. The idea is simple – the more guppy you have in a tank, the more impressive and beautiful they look.

Diet

Guppy fish adapt is easy to feed. It eats various food – artificial, frozen, live. The fish gladly feeds on flakes, pellets and other artificial food, but it’s better to choose food of famous trademarks. A good portion of a guppy’s diet can come from commercially available fish flakes or pellets specifically formulated for tropical fish. Look for high-quality fish foods that provide a balanced mix of proteins, fats, and carbohydrates. Opt for fish foods that are specifically labeled for guppies or tropical community fish.

As for the live food, favors bloodworm, tubifex, brine shrimp, corethra. It’s important to keep in mind, that guppy fish has small mouth and stomach and the food should be also small sized.

How often should you feed guppies? The best thing is to feed 2 times a day with portions that the fish can eat in 2-3 minutes. This helps to mimic their natural feeding habits and prevents overeating. It also ensures that they receive a consistent supply of nutrients.

Thus, except common food flakes get some flakes with vegetable supplements and feed with them twice a week to ensure healthy gastroenteric tract of the fish and high immunity.

Tank mates

Is a very peaceful fish that causes no trouble to its tank mates. Keep in mind, that this fish can and will eat its juveniles. Even the female after spawning will do this.

The guppy fish can be hurt by many other fishes, especially large and predator ones, which treat fish only as food. So, the conclusion is, that fishes like green terror, angelfish, jack dempsey won’t do as tank mates. The same is about fishes which will nip fins of males. These are — tiger barb, black skirt tetra, red-eyed tetra.

Guppy fish get along well with peaceful and small fishes like:

Gender differences: male vs female

Fancy guppies, like other guppy varieties, exhibit sexual dimorphism, which means there are noticeable differences between males and females. Here are some key differences between male and female fancy guppies:

  1. Size: Males are generally smaller in size compared to females. Adult males typically reach a size of 1.5 to 2.4 inches (3.8 to 6 cm), while adult females can grow up to 2 to 2.4 inches (5 to 6 cm) in length.
  2. Coloration: Male fancy guppies are known for their vibrant and striking colors. They often display a wide range of hues, including red, blue, yellow, green, orange, and black. Their bodies and fins are adorned with various patterns and color combinations, making them visually appealing. Females, on the other hand, have a more subdued coloration in comparison. They tend to have a drabber appearance, usually displaying a solid color or having more muted tones.
  3. Fins: Male fancy guppies have longer and more elaborate fins compared to females. They have a flowing dorsal fin, which can be quite long and eye-catching. The caudal fin (tail fin) of males is typically larger and more ornate, often displaying intricate patterns or shapes like a fan, lyre, or delta. Female guppies, while having fins, do not possess the same level of elongation or flamboyant designs. Their fins are generally shorter and less extravagant compared to males.
  4. Gonopodium: One of the most distinct differences between male and female guppies is the presence of a gonopodium in males. The gonopodium is a modified anal fin that is used for reproduction. It is elongated, curved, and pointed, serving as a reproductive organ. Females lack this specialized structure.
  5. Behavior: Male fancy guppies are typically more active and exhibit more energetic behavior compared to females. They may display courtship behaviors, such as fin displays and chasing, to attract females for mating. Females, while active in their own right, tend to be more reserved and less prone to showy displays.

Even among the guppy juveniles you can define males and females at rather early stages, because male are the first to get their full coloring.

Two males and female guppy fish
Female guppy fish

Breeding

One of the simplest fishes to breed is guppy fish. The thing is, that this fish is a live-bearing one. It means that the fish carries eggs inside its abdomen and spawns fully formed juveniles. During the first hours of their life juveniles will lay down and hide somewhere, but very soon they will start to swim and feed.

Guppies generally reach sexual maturity and become capable of breeding at a relatively young age. The exact age at which guppies can start breeding can vary depending on individual factors such as genetics, nutrition, and environmental conditions. However, in general, guppies can begin breeding as early as 2 to 3 months of age.

All you need for guppy breeding is… a male and a female. No, it’s even easier – one active and young male is enough to perform courtship over 3-5 females non stop. Which means that for successful breeding you can keep one male for 3-5 females, though there can be more males in a tank, because they don’t fight with each other, they only compete.

You may see the male haunting the female one for a long time, but this is ok and there is nothing you have to do about it. The thing is that during such haunting process the male fertilizes the female and soon you’ll have juveniles in your tank.

What do you need for breeding? Fresh and clean water, quality and good food and a couple of hetero fish. As a rule, guppy fish breed quite successfully in a common tank. But they also eat their juveniles and their tank mates either, which means that you should put pregnant female fish into a separate tank.

How to get that female is carrying eggs? The spot near the female anal orifice gets darker and the darker it is, the sooner the fish will spawn.

Put the female into a separate tank with the same water parameters and tank plants, where the juveniles can hide from her (yes, he is going to eat her kids). When the time comes, the female will spawn without issues.

Gestation period of the female lasts about 21-40 days depending on the tank water temperature. At the end, according to the fish age and size, it spawns from 10 to 200 juveniles.

One mating is enough for several fertilizations: the female spawns juveniles in portions – each 1-1.5 months. There were numerous cases when the female fish continued spawning 12-14 month later after mating. That’s why virgin female grown separately from male are used for selective breeding.

You should put the female away from the tank right after spawning. Juveniles care is the same simple, as that for the adult fish. Feed them with milled branded food (the same that you feed adult with).

Though it’s better to use special branded dry food for juveniles. You have to clean the tank with juveniles often to avoid food leftovers rotting. You can put some snails into the tank – apple snails or ram’s horn snails, for example. They won’t harm the juveniles, but they’ll eat the food leftovers.

It’s important to keep the tank water clean, but remember, that you can’t renew large amount water at one time.

The juveniles are small and weak, therefore changing of large water amount is dangerous for them. It’s better to renew about 10% of the total water volume once in 1-2 days or 25% of water once in a week.

Tank water temperature is crucial for juveniles and you must keep it about 24-26.5 C. Provided with proper care and diet the juveniles grow fast, so in 1-1.5 months they start getting their coloring.

FAQ

How to stop guppies from breeding?

The most straightforward method is to keep male and female guppies in separate tanks or compartments. By separating the sexes, you can ensure that they do not have the opportunity to mate and reproduce. Alternatively, you can choose to keep a single-sex group of guppies in your tank. By having only male or only female guppies, you eliminate the possibility of breeding. However, keep in mind that if you have females, they can still store sperm from previous mating encounters, and they may give birth to fry for some time.

Do guppy tails grow back?

Yes, guppy tails have the ability to regrow if they have been damaged or torn. Guppies possess a regenerative ability that allows them to regenerate their fins and tails to some extent.

When a guppy’s tail gets torn or damaged, the regeneration process begins. The damaged tissue starts to heal, and the fish’s body initiates the growth of new cells and fin tissue. Over time, the tail fin gradually regrows and regains its shape and size.

Why do guppy fishes die?

We can’t give you just one right answer for this question. Each case is a unique one. But more often than not the reason of the fish death is improper keeping. You must pay special attention to how often you renew water in a tank and how often you feed guppy. Everything is simple – food leftovers are like rubbish in your house, which is lying somewhere under the furniture and rots.

When such rubbish accumulates in the tank – the fish gets ill. You can help it by cleaning the tank bottom and renewing tank water.

How to identify that guppy female is pregnant?

Normally, female spawns juveniles once in a month, but the terms may vary depending on the tank water temperature and conditions. Remember when was the last time that the fish spawned and watch the fish. The spot on the abdomen of guppy fish that is ready to spawn becomes darker (these are juveniles eyes).

How does guppy breathe?

Just like all other fishes it breathes with oxygen dissolved in water. So, don’t forget to turn on aeration and water filtration.

How often should I feed guppy?

You must feed the fish every day with small portions of food 2-3 times a day. For example, in the morning and in the evening. Once in a week you can organize hunger day for the fish, but keep in mind that they will actively look for food and their own juveniles will quickly become their prey.

Why does guppy tails get torn?

There may be many reasons for this, but the most spread one is old water in the tank. The water accumulates ammonia and nitrates and these poison the fish and destroy its fins. Thus, regular water renew will save you from this problem.

However, if guppy lost its tail, this is a warning sign – either someone is nipping its fins and you have to study carefully the tank mates again, or the fish is ill with some infectious disease and you must examine other fishes in the tank even more closely.

Why is guppy tail gummed up?

Again this is either due to dirty, old tank water or some infection. Try to renew 20% of water once a week and monitor state of other fishes in the tank.

Why does guppy bent spine?

When a guppy exhibits a bent spine, it is commonly referred to as “curved spine” or “hunchback.” This condition, known as scoliosis or spinal deformity, can occur in guppies due to various reasons, including genetic factors, poor nutrition, or injury.

Why does guppy spawn only female?

There is no full and complete reply for this question yet. Possibly, some laws of nature get on the stage, when there is an exceeding number of males in the tank and the population compensates the female number to save itself.

Can guppies live alone?

Yes, you can, but it looks pretty sad…since, this is an active and joyful fish that likes company. If you are looking for an appealing, not demanding fish that easily lives alone, you may consider getting a betta fish.

Does guppy need oxygen and water filter?

Well, it’s not necessary, but it’d be good if you have them. You can get inexpensive internal water filter with a sponge. It’ll do the job quite well and won’t suck the fishes inside it. Keep in mind, if you have bought a filter and installed it high (to make the tank water surface move), you don’t have to buy aeration – you don’t need it at all.

Does guppy need bottom substrate and tank plants?

This is up to you. It is easier to clean an empty tank, but it doesn’t look nice. The juveniles won’t survive in it and also the adult fish like swimming among the tank plants. So, my choice is a tank with bottom substrate and plants.

Does guppy need light?

Fishes don’t need any light in general. The light that gets into the tank during a day is quite enough for them. These are tank plants which need light to grow.

Does guppy spawn eggs?

No, this is a live-bearing fish. Which means that the juveniles are born fully formed and ready to swim. Sometimes the juvenile may come out inside the egg, but it gets torn and the juvenile starts to swim. Occasionally, juvenile may have a yolk bag which it eats fast.

Does guppy sleep?

Yes, they do, but not like humans. This is more like an active rest, when at night the fish become less active, but still they continue swimming. Also it is better to turn off the lighting at night, though many aquarists don’t do this. But it is dark at night in the wild, isn’t it?

How many juveniles does guppy spawn?

This depends on the female – on its age and size. Usually, there are about 30-50 juveniles, but it can be even 200 sometimes.

Can guppies live in brackish water?

Yes. Although, they can stand living in brackish water, they’ll die in seawater. While guppies are primarily freshwater fish, some strains and wild populations can adapt to a certain degree of salinity. It’s important to note that not all guppies can tolerate brackish water, and their ability to adapt to salinity varies among individuals and strains. Wild populations of guppies from coastal areas or brackish water environments have developed some tolerance to salt.

Why do guppy swim on the tank water surface?

They breathe with oxygen dissolved in water and there is not enough oxygen in your tank. Why? Possibly, it is too hot in a tank or you haven’t cleaned it for a long time or maybe the tank is too crowded. You must definitely turn on aeration and water filtration (move the filter closer to the water surface to improve gas exchange) and add a portion of fresh water into the tank.

Why did my guppy jump out of the tank?

They can do it both accidentally and because the water in the tank isn’t good. For example, the water hasn’t been renewed for a while or the bottom substrate wasn’t cleaned. Insufficient amount of dissolved oxygen in the tank water may also be the reason (you can read about this above).

Why do guppies lose their color?

Stress is a significant factor that can cause color loss in guppies. Stressors can include poor water quality, sudden changes in temperature, aggressive tank mates, overcrowding, or inadequate hiding places. When guppies are stressed, they may become pale or dull in color as a response.