Species · Aquatic pet

Guppy

Poecilia reticulata

Tiny Caribbean and South American livebearer, bred into a thousand colourways and multiplying cheerfully in aquaria since the 1900s.

The guppy earns its reputation: hardy, colourful, active, cheap, and forgiving of beginner mistakes that would kill fussier fish. The single fact that decides everything is that guppies give birth to live young, constantly — a mixed-sex trio becomes a colony within months, no equipment or expertise required. Keep males only for a display with no arithmetic, or embrace the livebearer economy and know where the surplus goes. There is no third option in which they politely refrain.

At a glance

Lifespan: 2–4 years
Adult size: 3–6 cm; females larger
Minimum tank: 60 L
Water: Tropical fresh, heated
Weekly upkeep: Weekly partial water change
Diet: Quality flake, small and often — not much
Company: Groups; males-only avoids the population question
With children: Watch, don’t touch; a genuinely good first tank
Tankmates: Peaceful smalls; nothing that nips trailing tails

Varieties · 4 listed

Fancy males carry the colour and the tail; females are larger and plainer. Every strain is the same easy fish underneath.

Fancy
Cobra
Tuxedo
Moscow blue

Right for you if

A first tropical tank wants reliable, colourful, active residents.
You have decided the males-only question deliberately, either way.
Small, frequent feeding and weekly water changes fit the routine.
A moving display of colour is the point more than individual pets.

Wrong for you if

A mixed-sex tank with no plan for fry — the plan makes itself, in dozens.
The tank holds fin-nippers or anything mouth-sized larger.
Unheated. Guppies are tropical, whatever the fair said.
You want fish with decade-scale lifespans; livebearers burn brighter and shorter.

Welfare and sourcing — read this part

Most fish disease follows stress, poor water quality, overcrowding and skipped quarantine¹ — and a livebearer colony overcrowds itself on schedule. Population control is water quality control; decide the male-female question before the tank does.
Buy active, tight-finned fish from sparse, clean shop tanks, and quarantine — mass-bred guppies travel through crowded supply chains, and the fortnight in a spare tank catches what the shop’s lights hide.

Sources

Disorders and Diseases of Fish. MSD Veterinary Manual 2026. Accessed 2026-09-05. International MSD Veterinary Manual Many of the disorders and diseases that occur in fish are the result of stress, poor water quality, overcrowding, and failure to quarantine. New tank syndrome is ammonia accumulating when fish are added before the biological filter works, typically in the first one to three weeks. Ich (white spot) is a common protozoal infestation whose fast reproduction is what makes it deadly.

Every source here was checked, not recalled. Where this page makes a health statement and no source appears against it, that is not an oversight we have hidden — it means the claim is not yet sourced, and the build reports how many are in that state.

Availability, registration and keeping requirements differ from place to place. Check the rules where you live before you commit to any animal — we describe animals, not law.