Fellow Creatures
Pet match quiz
Guppy
Freshwater Fish

Guppy

Poecilia reticulata

Colourful livebearer that breeds readilyBeginner

Lifespan
2-3 years
Size
1.2-2.4 in
Social needs
Social; keep 6+ together
Time
10-15 min daily; weekly water change
Cost
Low
Diet
Omnivore (flake, micro-pellet, veg, live foods)

Overview

What is this animal?

  • Guppies are small, peaceful livebearers native to northeastern South America, with males known for their patterned tails.
  • Hardy and adaptable, they are among the most widely kept aquarium fish.
  • They breed readily in the home aquarium, which is part of their appeal and also their main pitfall.
  • A mixed-sex tank quickly fills with fry, so plan for population control or a single-sex group before you buy.

Temperament

  • Guppies are sociable, active, and peaceful, best kept in groups of six or more where they shoal loosely.
  • Males court females persistently, so keep at least two, and better three, females to every male, or a males-only group of six to ten.
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  • They mix well with other calm community species but may have their fins nipped by boisterous tankmates.
  • A mixed group will produce fry continuously, which adults will eat unless plenty of cover is provided.

A good fit for

  • Absolute beginners and children's first tanks
  • Community aquariums with peaceful species
  • Keepers who enjoy colour and breeding
  • Planted 24 in community aquariums

Common mistakes to avoid

  • Unplanned breeding overwhelming the tank
  • Buying weak, mass-bred stock prone to disease
  • Keeping males with too few females
  • Assuming hardiness means dirty water is fine

Enclosure

Minimum 15 gallons, for a group of 6

Cannot be kept alone. The minimum is 6, and the space above is for that group.

  • A heated, filtered, cycled tank of at least 15 US gallons and 24 in long suits a group: Practical Fishkeeping gives a 24 x 12 x 12 in tank as the minimum for a group of guppies.
  • A mixed-sex group that is allowed to breed needs more.
  • Hold the temperature at 72-79°F.
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  • Guppies prefer slightly hard, alkaline water and appreciate planting for cover and for fry to hide among.
  • They are gentle swimmers and dislike strong currents.
  • Keep nitrate low with weekly partial water changes, as guppies are sensitive to dirty water despite their reputation for toughness.
  • A secure lid prevents the occasional jumper from escaping.

Check your enclosure

Supplies

Setup

  • Tank and stand
  • Filter
  • Heater and thermometer
  • Substrate, plants and decor
  • Liquid test kit
  • Dechlorinator and starter supplies

Ongoing

  • Quality tropical flake or micro-pellet
  • Spirulina or vegetable flake
  • Frozen brine shrimp and daphnia
  • Frozen or freeze-dried bloodworm
  • Veg clip for courgette and spinach
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  • Baby brine shrimp hatchery or frozen equivalent for fry
  • Fine net for removing leftovers

Safe substrate: Fine, smooth sand · Smooth, rounded fine gravel (not for loaches or sand-sifting cichlids; sand is better for corydoras) · Bare bottom (quarantine and grow-out only)

Work out the cost

Care routine

Daily

  • Check temperature and equipment
  • Feed
  • Head-count and look everyone over

Every few days

  • Top up evaporationevery 3 days

Weekly

  • Test the water
  • Water change and gravel vacuum
  • Wipe the front glass only
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Every few weeks

  • Trim and thin the plantsevery 2 weeks

Monthly

  • Check supplies and reagent dates
  • Replace or recharge chemical media, if you use any (skip it in a blackwater tank)
  • Review the fry plan
  • Rinse the filter media

Health review: Quarterly stocking and health review, every 3 months

Tools

Is your enclosure big enough?Check your measurements against the recommended sizeWhat will it cost?Setup, monthly and over its whole life, itemisedIs this ammonia reading dangerous?Works out the toxic part from your pH and temperature

Care in depth

Diet

Omnivore (flake, micro-pellet, veg, live foods)
  • Guppies are omnivores and do best on a varied diet.
  • Offer a quality flake or micro-pellet as the staple, rotating in blanched vegetables, spirulina, and frequent treats of frozen or live brine shrimp, daphnia, and bloodworms for colour and condition.
  • Feed small amounts once or twice daily, only what is cleared in a minute or two.
  • Their small stomachs make overfeeding easy, which fouls water and contributes to obesity and bloating in well-stocked tanks.

Health

Signs of good health, and the common problems
  • Mass-bred guppies can be genetically weak, so buy from reputable sources and quarantine new arrivals.
  • Common problems include fin rot, ich, and protozoan ailments that follow chilling or unstable parameters.
  • Stable warmth and clean water prevent most issues.
  • Watch for clamped fins, white spots, or a wasting, hollow belly that can signal internal parasites.
  • Acclimatise slowly to avoid temperature and pH shock, and avoid overcrowding, which is a frequent trigger for outbreaks.

Is this urgent?

6 warning signs and how fast to act, 3 of them right away

In a fish tank the patient is usually the water. Test before you treat: dosing a healthy tank for a disease it does not have makes things worse.

Go now

Any detectable ammonia or nitrite in a stocked tankLarge water change now with dechlorinated, temperature-matched water. Stop feeding. Test again in 12 hours. Both are directly toxic. How toxic the ammonia reading is depends on pH and temperature, so the same number can be harmless or lethal.
Now
Fish gasping at the surface with fast gill movement, or crowding the filter outflowIncrease surface movement now (gently in a betta or gourami tank, without creating a strong current), then test the water. Either the oxygen has crashed or the gills are being chemically burned. Both are hours-scale problems. Bettas, gouramis and corydoras rise to gulp air as part of normal breathing; the warning is constant gulping, fast gill movement, or the whole group hanging at the top.
Now
Sudden deaths, more than one fish in a dayTest ammonia, nitrite, nitrate and temperature before doing anything else. Do not add medication yet. Multiple simultaneous deaths usually point at the water or the equipment rather than a pathogen, so rule those out first.
Now

Today

Flashing: repeatedly scraping against decor or substrateTest the water, then look closely for parasites. Irritation is either chemical or parasitic; the test tells you which before you medicate.
Today
White salt-grain spots over the body and finsBegin the appropriate treatment today and check the temperature. The parasite's life cycle is temperature-driven, and it multiplies with every cycle you wait.
Today

Soon

Clamped fins, hiding, or refusing food for more than two daysTest the water and review recent changes. Usually the earliest visible sign of a parameter drifting.
A few days

Never add a new fish to a tank that is not fully cycled, and never treat blind. A test kit is cheaper than the fish.

This is general guidance for a healthy adult, not a diagnosis. An exotics vet who knows your animal always overrides it, and the time to find one is before you need one.

Bedding and substrate

3 safe, 4 with a caveat, 2 to avoid

Substrate in an aquarium is a filter as much as a floor. Most of the biology lives in and on it.

Safe

Fine, smooth sandCorrect for corydoras, kuhli loaches, eartheaters such as rams and acaras, and anything else that sifts or burrows. Barbels wear away on sharp gravel.
safe
Smooth, rounded fine gravel (not for loaches or sand-sifting cichlids; sand is better for corydoras)Rinse thoroughly before use. Grain size should be too large to swallow and too small to trap food. Kuhli loaches need sand to burrow into and rams and acaras sift mouthfuls of it; bronze and panda corydoras manage on smooth fine gravel, but sterbai corydoras need sand.
safe
Bare bottom (quarantine and grow-out only)Legitimate for quarantine and grow-out tanks. Easy to clean, but it holds far less biological filtration, and it is no long-term home for burrowing loaches or sand-sifters.
safe

With a caveat

Crushed coral or aragoniteDeliberately raises hardness and pH. Correct for rift-lake cichlids, wrong for soft-water species.
with a caveat
Aquasoil for planted tanksExcellent for plants, but most active soils soften the water and pull pH and KH down for months, and many leach ammonia for the first weeks. Right for soft-water species; wrong for hard-water animals (livebearers, rainbowfish, goldfish, and snails, whose shells erode in soft, acidic water) unless you test GH and KH and remineralise. Cycle around it; do not stock into it.
with a caveat
Very deep sand bedsAnaerobic pockets form below about 2 inches in still sand. Either keep it shallow or keep it stirred.
with a caveat
Painted or coated gravelUsually fine, but coatings chip. Test a handful in a jar for a week first.
with a caveat

Never

Sharp or angular gravel with bottom-dwellersWears down barbels and leads to infection in corydoras and loaches.
never
Anything containing metal, limestone of unknown origin, or shells in a soft-water tankSlowly alters chemistry in ways that are hard to diagnose later.
never

This is our general list for freshwater fish. We have not built one specific to Guppy yet.

Top resources for more info

Independent creators and organisations we would send a friend to. We have no affiliation with any of them, and nothing here is sponsored. Links checked 2026-10-22.

YouTubers

Girl Talks FishCare how-tos by fish type, tank setup and beginner mistakes (the host works for Aquarium Co-Op, a retailer)Aquarium Co-OpSpecies care guides, filtration and fish health (run by a retailer)Prime Time AquaticsSpecies profiles, stocking and water chemistry explained plainly

Sites

Keep going

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Is your enclosure big enough?

These are the smallest sizes that give good conditions, not legal minimums. More room is always better.

Minimum 15 gallons, for a group of 6

Every figure, and where it comes from
Minimum volume15 gallons
Swimming length24 in minimum. A tall tank of the right volume is still the wrong shape.
CompanyCannot be kept alone. The minimum is 6, and the space above is for that group.
The recognised standards do not agree on this one
Practical Fishkeeping (guppy care guide): 24 x 12 x 12 in, 14 gal, as the minimum for a group. The tank this site uses, taken as a standard US 15-gallon so it sits above Austria's legal minimum: room for six to ten males, or one or two males with four females. A mixed-sex group that breeds needs more. Checked 2026-10-23.
Seriously Fish (Poecilia reticulata): 18 x 12 in base, about 11 US gal. A smaller base than the one used here. Checked 2026-10-23.
Austrian legal minimum (2. Tierhaltungsverordnung, Anlage 5): 24 x 12 x 12 in (14 gal), and no fish kept permanently in less than 14 gal. A legal minimum, recorded for context. Checked 2026-10-23.

What it really costs

Setup, monthly, first year and across a whole life, itemised and with the electricity worked out from the actual wattage. Published figures for the same animal disagree by a factor of four, so the calculator shows ranges rather than picking one.

My kit says 0.25 ppm. Is that dangerous?

A liquid kit measures total ammonia, but only the un-ionised fraction is really toxic, and that fraction is governed by pH and temperature. Each whole pH unit multiplies it roughly tenfold. So the same reading can be nearly harmless in one tank and lethal in another; this works out which one you are in.