Guppy care guide: tank, water, tank mates and breeding

01

Guppy care basics

The guppy is a small livebearer famous for the endless color and fin patterns of its males. It is one of the classic beginner fish: hardy once settled, easy to feed and always on the move. The main challenges are buying healthy stock, keeping the water clean and managing the fry that will appear sooner or later.

Like any tropical fish, guppies need a heater and a filter, and the tank should be fully cycled before they arrive. Pet-store fancy guppies are heavily line-bred, which can make them less robust than their wild ancestors, so stable conditions matter even more.

• Tank: 10 gallons for a trio or small group, 20 gallons for a mixed colony
• Heater: adjustable, set to about 76–78 °F (24–26 °C)
• Filter: gentle flow; a sponge filter is safe for fry
• Plants: dense and floating plants give fry and harassed females cover
• Lid: guppies occasionally jump

02

Origin and natural habitat

Wild Poecilia reticulata come from northeastern South America, including Venezuela, Guyana and northern Brazil, plus islands such as Trinidad and Tobago and Barbados. They live in streams, ponds, ditches and even brackish edges, often in warm, hard, slightly alkaline water. Because they eat mosquito larvae, guppies have been introduced to many tropical regions, where they now live wild.

Wild guppies are much smaller and less flashy than the fancy strains in stores. Decades of selective breeding produced cobra, tuxedo, mosaic, grass, delta and many other varieties.

03

Adult size and guppy lifespan

Males reach about 1.2–1.4 inches (3–3.5 cm) of body length, plus their large tail. Females are larger and heavier, usually 1.6–2.4 inches (4–6 cm), with smaller tails and a dark gravid spot near the vent when pregnant.

The typical guppy lifespan is about 2–3 years. Fancy males with very long fins often live a little less. Stable temperature, clean water and avoiding constant breeding stress in females help them reach the upper end of that range.

04

Tank size and setup

A 10-gallon (38 L) tank is the practical minimum for a small group, such as one male and two or three females or a group of males only. Because guppies multiply quickly, many keepers start with 20 gallons (75 L). For ideas on combining them with other small species, see our list of the best fish for a 10-gallon tank.

Guppies swim in the upper and middle water layers. Leave open swimming space at the front and plant the back and sides densely. Fine-leaved plants and floating plants such as hornwort, water sprite or frogbit give newborn fry a place to hide.

05

Water parameters

Guppies prefer moderately hard, slightly alkaline water, which suits much of the tap water in the US. Very soft, acidic water is a common cause of poor health in this species. Treat new water with a water conditioner and check our guide to aquarium water parameters if your readings fall outside the ranges below.

06

Diet and feeding

In the wild, guppies eat insect larvae, small crustaceans, algae and plant matter. In the tank, a quality micro-flake or small pellet makes a good staple. Add frozen or live foods such as baby brine shrimp, daphnia and bloodworm pieces a few times a week, and a spirulina-based food for the plant part of their diet.

Feed small amounts once or twice a day, only what they eat in about a minute. Guppies always look hungry, and overfeeding quickly fouls the water in small tanks. Pregnant females and growing fry benefit from slightly more frequent, smaller meals.

07

Behavior and guppy tank mates

Guppies are peaceful and social. Males display constantly and chase females, so a ratio of one male to two or three females spreads the attention and reduces stress. An all-male tank is a good option if you want color without fry; males rarely injure each other.

Good guppy tank mates are small, peaceful fish that share similar water: platies, endlers, corydoras, bristlenose plecos and otocinclus, plus snails and adult shrimp (shrimp babies may be eaten, and guppies will eat each other’s fry too). Avoid fin nippers such as tiger barbs, bettas, which may attack males' fins, and large fish like angelfish that see guppies as food. Our full guppy tank mates guide includes stocking examples.

• Good matches: platies, endlers, corydoras, bristlenose pleco, otocinclus, nerite and mystery snails
• Use caution: cherry shrimp (fry eaten), tetras that prefer soft water
• Avoid: bettas, tiger barbs and other fin nippers, angelfish, large cichlids

08

How to breed guppies

Breeding guppies takes almost no effort: put males and females together and fry will appear. Females give birth to live, free-swimming young after a gestation of roughly 4 weeks, usually anywhere from a few to several dozen fry per brood. A female can store sperm and produce several broods from a single mating, so a new female may give birth even without a male in your tank.

Adults eat fry, so survival depends on cover or separation. Dense plants and floating plants save many babies; a separate grow-out tank saves more. Breeding boxes work for a short time but stress some females. Feed fry crushed flakes, powdered fry food or baby brine shrimp several times a day. For a full walkthrough, read how to breed guppies.

09

Common guppy diseases

Guppies sold in large numbers can carry parasites and bacterial infections, so quarantine new fish for two to four weeks when you can. Most problems in an established tank point back to water quality, temperature swings or very soft water.

Contact an aquatic veterinarian for persistent or spreading problems, and always follow the label of any treatment.

10

Recommended gear

A sponge filter is ideal for guppy tanks because it provides biological filtration without sucking in fry; see our best sponge filter picks. Pair it with a reliable adjustable heater, sized at roughly 3–5 watts per gallon; our best aquarium heater guide compares models with accurate thermostats.

Add a liquid test kit, a lid and plenty of plants. These basics cover almost everything a guppy colony needs.