Quick answer: Keep guppies in a cycled freshwater tank at least 60 cm long, in a group of five or more. Use stable warm water and a small staple food. Mix sexes only if you want live young.
A guppy is Poecilia reticulata, a livebearing freshwater fish the USGS lists at 2.5 cm SL for males.
This page is a research-desk brief on tank setup, water, feeding, and breeding. We did not keep a colony, run water trials, or treat sick fish.
We included only staple foods with published protein and fat numbers. We also used species facts from the USGS and FishBase. We left out medicines, show-strain rules, and unlabeled foods.
How we chose what to cover
One rule decided every section: a fact stayed only if a maker page, the USGS, or FishBase published the number.
Our research team analyzed four currently sold staple foods and compared their protein, fat, and fiber figures. We did not rank the foods or sort them by price.
We skipped disease charts and medication lists because those topics sit outside a research desk. We also skipped gallon-only stocking slogans, since FishBase publishes a tank length instead.
What a guppy is
A guppy is a small livebearing freshwater fish with a large size gap between the sexes.
The USGS species profile names the fish Poecilia reticulata and lists the older names Lebistes reticulatus and millions fish. The same USGS page lists adult males to 2.5 cm SL and adult females to 6 cm SL.
FishBase lists a different male maximum on its summary page: 5.0 cm SL for males and 6.0 cm SL for females. It also lists a common male length of 2.8 cm TL.
Those two male numbers do not match, so do not collapse them into one size. Treat the USGS 2.5 cm SL figure and the FishBase 5.0 cm SL figure as a published clash.
FishBase says males are about half the size of females and have a colorful tail. The male anal fin is a gonopodium used for internal fertilization.
FishBase lists this ray count for identification:
- Dorsal soft rays: 7 to 8
- Anal soft rays: 8 to 10
- Dorsal spines: 0
- Anal spines: 0
The USGS profile places the native range in the southern Lesser Antilles and northern South America, from western Venezuela to Guyana. FishBase places native waters in Venezuela, Barbados, Trinidad, northern Brazil, and the Guyanas, and it notes wide introductions elsewhere.
The USGS profile lists locally established warmwater sites in six places: Hawaii, Idaho, New Mexico, Nevada, Texas, and Wyoming. It also reports records from California, Colorado, Connecticut, Missouri, Montana, and Wisconsin.
FishBase lists the IUCN Red List status as Least Concern and gives the assessment date as 18 May 2020. Do not mix SL and TL when you compare those length figures.
Tank setup that matches published length
FishBase, not a gallon slogan, sets the tank size we use on this page.
FishBase lists aquarium keeping in groups of 5 or more and a minimum aquarium size of 60 cm. Sixty centimeters is about 24 inches of tank length, which is a length rule rather than a volume rule.
Build the box around that length and around live young, because FishBase says one birth can add 20 to 40 fry. Two females can add 40 to 80 fry in one cycle, so the 60 cm length has to hold adults and that pulse of young.
A mixed-sex group will keep adding those births unless you separate the sexes. If you cannot add length, keep one sex only.
Use this setup list:
- Pick a tank at least 60 cm long, per FishBase.
- Plan for a group of 5 or more, per FishBase.
- Cycle the tank before the first fish go in.
- Add a heater, a gentle filter, and a tight lid.
- Add plants or other cover so fry can hide.
Do not dump extra fish outdoors. The USGS profile says most United States introductions likely came from fish-farm or aquarium releases. FishBase says Australian wild stocks came from discarded pets before the 1970s.
Water numbers from FishBase
Hold temperature inside the published tropical band and keep pH inside the published range.
FishBase lists these water figures on the species summary:
- pH range: 7.0 to 8.0
- dH range: 9 to 19
- Temperature band: 18°C to 28°C (about 64°F to 82°F)
- Survival note: 23°C to 24°C (about 73°F to 75°F) in quiet, planted water
The USGS profile says the species needs warm water to thrive, which matches the FishBase tropical label. Test source water before you buy fish, and leave tap water alone if it already sits in that pH and hardness band.
If your tap sits far outside pH 7.0 to 8.0, change the plan instead of forcing a fast swing. Keep ammonia and nitrite at zero after the cycle.
Those two toxins are not given as guppy-specific limits on the pages we used. Still treat any reading above zero as a reason to stop adding fish.
Do a regular water change and remove leftover food. Dirty water, not a missing gadget, is the usual failure.
Feeding from maker labels
Compare staple labels by protein, fat, fiber, and form, then feed only what fish finish in minutes.
FishBase says wild guppies eat zooplankton, small insects, and detritus, which is an omnivore pattern. A complete small flake or pellet can be the daily staple.
Hikari’s page for Tropical Fancy Guppy says to feed two to three times daily, and only the amount fish will finish in a few minutes. Our research team analyzed four currently sold staples and built the WaterPuppy Staple Label Sheet from those maker pages.
Listed minimum crude protein ran from 39% to 50%, an 11-point spread. Listed minimum crude fat ran from 5% to 11%, and listed maximum crude fiber was 2% on two foods and 5% on two foods.
Only Hikari Tropical Fancy Guppy names guppies on the maker page. The other three foods are general tropical or community staples.
Hikari’s page says the pellet becomes soft quickly yet does not dissolve in water. Omega One’s page lists Alaskan salmon and whole herring first. NorthFin’s Krill Gold page lists whole Antarctic krill meal first and says the food is made in Canada.
| Product | Form | Min. crude protein | Min. crude fat | Max. crude fiber | Maker-listed use |
|---|---|---|---|---|---|
| Hikari Tropical Fancy Guppy | Slow-sinking pellet | 50% | 8.0% | 2.0% | Guppies and other very small tropical fishes |
| Omega One Freshwater Flakes | Flake | 39% | 11% | 2% | All freshwater fish |
| NorthFin Krill Gold / Krill Pro | Slow-sinking pellet, 1 mm to 6 mm | 42% | 5% | 5% | Freshwater and saltwater carnivores and omnivores |
| NorthFin Community Flake | Flake | 40% | 5% | 5% | Freshwater herbivores and omnivores |
Hikari’s page lists a 0.77 oz (22 g) pack as item 22102. It lists moisture at a 10% maximum, ash at an 18% maximum, and phosphorus at a 1.0% minimum.
Omega One’s Freshwater Flakes page lists moisture at an 8.5% maximum and ash at an 8% maximum. Pack sizes on that page run from 0.42 oz to 5 lb.
NorthFin’s Krill Gold page lists a 1 mm pellet as the smallest size, which is the size that fits a small mouth. Larger 2 mm, 3 mm, and 6 mm pellets are listed for bigger fish.
NorthFin’s Community Flake page lists 65 g and 350 g packs and does not name guppies. Use one staple as the daily food, and if you add a second form, still follow the Hikari time rule.
Skip any pellet that is 6 mm wide, because that size is the wrong tool for a guppy mouth.
Breeding and fry
Mixed sexes produce live young on a weeks-long cycle, and adults may eat those young.
FishBase says males mature at 2 months and females mature at 3 months. Females can store sperm and may produce young every four weeks.
FishBase lists a gestation period of four to six weeks and 20 to 40 live young in a birth. Pregnant females show a dark triangle between the anal and pelvic fins, per FishBase.
There is no parental care, and parents may eat the fry. If you want fry to survive, use this list:
- Keep dense plants or a separate rearing box.
- Feed adults only what they finish, so they hunt less.
- Move the female before birth only if you can do it without rough handling.
- Expect another brood about four weeks later if a male is present.
If you do not want fry, keep only males or only females. One leftover male can restart the cycle because females can store sperm.
Do not release extra fry. The USGS profile ties aquarium releases to wild introductions, and FishBase repeats that warning for Australia.
FAQ
How big does a guppy get?
The USGS profile lists males to 2.5 cm SL and females to 6 cm SL. FishBase lists males to 5.0 cm SL, females to 6.0 cm SL, and a common male length of 2.8 cm TL. Plan space for the larger female number.
What tank size does a guppy need?
FishBase lists a minimum aquarium size of 60 cm and a group of 5 or more. That is a length rule, not a gallon slogan. A shorter box can crowd an active group and leave no room for fry.
What water does a guppy need?
FishBase lists pH 7.0 to 8.0, dH 9 to 19, and 18°C to 28°C, with a 23°C to 24°C survival note. The USGS profile says the species needs warm water to thrive. Keep the reading steady inside that band.
What should I feed a guppy?
FishBase says the wild diet is zooplankton, small insects, and detritus. On the WaterPuppy Staple Label Sheet, maker pages list 39% to 50% minimum crude protein. Hikari Tropical Fancy Guppy is the only one of the four foods that names guppies. Hikari’s page says to feed two to three times daily, only what fish finish in a few minutes.
How many young does a guppy have?
FishBase lists 20 to 40 live young after a four- to six-week gestation. It says females may produce young every four weeks. Adults may eat those young.
Can I keep one guppy?
FishBase lists aquarium keeping in groups of 5 or more. A single fish falls below that published group size. If you keep one sex only, you still need that group count.
Should I release extra guppies?
No, extra fry belong in another tank, not in a creek. The USGS profile says most United States introductions likely came from fish-farm or aquarium releases. FishBase says discarded pets built wild stocks in Australia before the 1970s.
