Quick Facts
- Common Names: Guppy, Millionfish, Rainbow Fish
- Scientific Name: Poecilia reticulata
- Adult Size: Males: 0.7-1.4 inches (1.8-3.6 cm); Females: 1.5-2.5 inches (3.8-6.4 cm)
- Lifespan: 2-5 years in captivity (typically 2-3 years)
- Care Level: Beginner – Very easy and adaptable
- Temperament: Peaceful toward other species; males moderately aggressive toward each other
- Diet: Omnivore
- Minimum Tank Size: 10 gallons for 5-7 guppies
- Recommended Tank Size: 20-40 gallons for active schools and breeding
- Temperature Range: 64-84°F (18-29°C); Optimal: 76-78°F (24-25°C)
- pH Range: 6.5-8.5; Optimal: 7.0-8.0 (slightly alkaline)
- Water Hardness: 8-30 dGH (moderate to hard water)
- Breeding Difficulty: Very Easy – No special conditions required
- Breeding Method: Livebearer – eggs fertilize internally; females give birth to live fry
- Native Range: South America: Trinidad and Tobago, Venezuela, Brazil, Guyana
Introduction
Guppies are the perfect entry point into the aquarium hobby. If you’re thinking about your first aquarium or looking for easy-to-keep, stunning fish, guppies are hard to beat. These colorful little livebearers come in virtually unlimited color patterns—from metallic blues to vibrant reds to fancy koi-inspired patterns. Males sport spectacular, elaborate tail fins that seem to flow like silk in the water. They’re peaceful, active, breed readily without any special effort, and bounce back from beginner mistakes better than almost any other fish. Whether you’re just starting out or an experienced aquarist looking to add color to a community tank, guppies deliver.
Video Overview
Appearance
Guppies are compact, elegant fish with striking sexual dimorphism that makes them instantly recognizable. What you’re getting depends entirely on whether you’re looking at a male or female.
Male Guppies: Smaller and more slender (0.7-1.4 inches), with a streamlined body built for agility. The real show is in the tail and dorsal fin—both are dramatically enlarged and ornate. The tail is typically fan-shaped, lyre-shaped, or sword-shaped depending on the strain you’re keeping. The dorsal fin is tall and decorated with patterns. Males are like little underwater peacocks, constantly showing off their colors.
Female Guppies: Noticeably larger (1.5-2.5 inches), with a rounder, more robust body. Their coloration is subdued compared to males—typically silver, gray, or light gold with minimal patterns. Their tail and dorsal fins are shorter and less ornate. When carrying eggs, females develop a darkened “gravid spot” near the anal fin and appear noticeably plumper.
Coloration: Wild-type guppies are metallic blue-green with red or orange concentrated on the tail. But selective breeding has created virtually unlimited color varieties: platinum white, deep red, electric blue, golden yellow, black, dalmatian spots, koi patterns, and metallic iridescent scales. The palette is truly limitless. Color expression depends on genetics (most important), environment (stress, lighting), and diet (specialized foods can boost existing colors but can’t create new ones from genetics).
Key trait: The gonopodium (modified anal fin) in males is the most reliable gender indicator. It’s a long, narrow, tube-like structure used for reproduction. Females have a normal fan-shaped anal fin. This makes gender identification straightforward from juvenile stages forward.
Creating the Right Environment
Guppies are adaptable and forgiving, but they truly thrive in planted tanks designed to minimize stress and show off their colors.
Dark Substrate Makes Colors Pop: Use fine black, dark brown, or dark gray sand or small gravel. Against this background, guppy colors absolutely shine. Vibrant reds glow, blues appear electric, metallics reflect beautifully. Beyond aesthetics, dark substrates psychologically reduce stress—guppies appear more confident and colorful in tanks with good visual contrast.
Planted Tank with Open Swimming Areas: Guppies appreciate plants for security and hiding spots, especially females escaping male attention. Use tall stem plants (Amazon Sword, Ludwigia), broad-leafed plants (Anubias, Java Fern), and floating plants (water lettuce, duckweed). Floating plants are particularly useful for reducing stress and providing refuge. But don’t turn the entire tank into a jungle—leave open midwater areas where they can swim and school naturally. The balance between cover and open space is what brings out their personality.
Driftwood and Hardscape for Territory Breaking: Driftwood, rocks, and artificial caves create natural breaking lines of sight. This is especially important for all-male tanks, as it significantly reduces male-on-male aggression by preventing constant visual confrontation. Strategic hardscape placement allows dominant males to maintain territory without constant chasing.
Moderate to Bright Lighting: Unlike blackwater species that prefer dim lighting, guppies tolerate and even prefer brighter conditions. Moderate to bright lighting (20-40 lumens per liter) highlights their colors beautifully and stimulates natural behavior. Use cool white (6500K) to emphasize blues and metallics, or warm white (3000K-4000K) to emphasize reds and oranges. Full-spectrum (5000K-6500K) provides balanced color rendering.
Care Basics
Water: Guppies prefer warm, slightly alkaline, hard water. Maintain 76-78°F (ideally), pH 7.0-8.0, and 8-30 dGH (hard water). They’re remarkably tolerant of variations—they can survive in pH 6.5-8.5 and temperatures 64-84°F—but they thrive in these optimal ranges. The remarkable adaptability is what makes them so beginner-friendly; they adjust to different tap water conditions better than almost any tropical fish.
Tank Size: Start with 10 gallons minimum for 5-7 guppies, but 20 gallons is strongly recommended for community setups and breeding. Larger tanks provide better water stability and allow for natural schooling behavior. Calculate 2 gallons per guppy as your safe minimum.
Food: Guppies are omnivores needing variety. Use high-quality flakes or micro pellets as your staple (soak briefly before feeding). Supplement regularly with frozen foods: baby brine shrimp, daphnia, bloodworms, mosquito larvae. Live foods (newly hatched brine shrimp, microworms) are excellent for conditioning breeding stock and enhance coloration. Feed once or twice daily in portions they finish in 1-3 minutes. Remove uneaten food immediately.
Equipment: You’ll need a reliable heater (50-100 watts depending on tank size) to maintain consistent 76-78°F. A sponge filter or gentle hang-on-back filter works perfectly for guppies—they prefer calm water, not strong currents. Flow should be 2-4 times your tank volume per hour. A tight-fitting lid is recommended to prevent accidental jumps and reduce evaporation. Test kit for ammonia, nitrite, nitrate, and pH is essential for monitoring.
Maintenance: Perform 25% water changes every 1-2 weeks in established tanks. In breeding tanks, increase frequency to 25-50% twice weekly to maintain quality and trigger spawning. Never allow more than 4 weeks between water changes. Always match replacement water temperature to tank water (within 1-2°F). Test ammonia and nitrite weekly—they must stay at 0 ppm. Keep nitrates below 30-40 ppm for optimal health.
Behavior
Guppies are active, curious, social fish that keep you entertained throughout the day. Males are particularly bold and showy, constantly displaying their colorful fins.
What to Expect: In established tanks with good-sized groups, guppies are confident explorers. They’ll investigate new decorations, eagerly approach feeding areas, and display beautiful interactive behavior during dusk periods. They’re active near the surface but swim all water levels, constantly foraging. Males actively pursue females (this is normal mating behavior, not aggression, though it can become stressful with improper ratios).
Personality: Guppies are curious, bold, social fish. They’re not aggressive toward other species but do display territorial behavior toward each other, particularly males. Males establish loose dominance hierarchies through characteristic “headstand” displays (45-90 degree body angles), fin spreading, and subtle chasing. These are normal, harmless behaviors, though they do indicate social structure.
Activity Patterns: Most active during early morning and early evening, with peaks at dusk when lighting gradually fades. They’re nearly always moving—foraging, exploring, displaying. They become slightly less active during bright midday hours in heavily lit tanks but are generally the most active fish compared to other community species.
Male Aggression: In all-male or male-heavy tanks, expect chasing and territorial displays. This is normal and rarely results in injury, but it’s stressful. The solution: adequate space (20+ gallons for 5-7 males), plenty of hiding spots (plants and hardscape), and proper feeding (disperse food widely so dominant males don’t monopolize it). In mixed tanks, maintain 2-3 females per male to diffuse male attention and reduce stress.
Tank Mates
Guppies are peaceful community fish perfect for multi-species tanks. They’re compatible with most non-aggressive species.
Good Choices:
- Other tetras: Neon tetras, Cardinal tetras, Ember tetras, Black Skirts. Share peaceful temperament and work well in communities.
- Small rasboras: Harlequin rasboras, Chili rasboras. Compatible in size and temperament.
- Corydoras catfish: Bronze, Pygmy, Panda corydoras. Occupy bottom layer; peaceful and compatible.
- Otocinclus catfish: Small, peaceful bottom-dwellers. Keep in groups of 2-3.
- Peaceful gouramis: Honey gouramis, Sparkling gouramis. Compatible in size and temperament.
- Endlers livebearers: Nearly identical to guppies; extremely compatible (may interbreed).
- Freshwater shrimp: Cherry shrimp in heavily planted tanks; guppies may eat shrimplets, so dense cover essential.
- Snails: Mystery snails, Nerite snails. Peaceful and occupy different ecological niches.
- Platies and mollies: Similar body shapes and water requirements; peaceful and community-suitable.
Be Careful With:
- Male bettas: Highly variable results. Can work in heavily planted 20+ gallon tanks, but betta temperament varies; some attack guppies, others are fine.
- Larger tetras: Can occasionally chase or compete with guppies.
- Tiger barbs: Can harass guppies through nipping and aggressive chasing.
- Dwarf gouramis: Can become aggressive during breeding; may chase smaller guppies.
Avoid Completely:
- Angelfish (adult): Will predate on guppies once they reach 4+ inches.
- African cichlids: Completely incompatible—too aggressive.
- Large predatory fish: Oscars, Jacks, Redtail catfish will eat guppies.
- Pufferfish: Aggressive fin-nippers targeting small, colorful fish.
- Goldfish: Completely different temperature needs and will eat small fish.
Group Size: Keep guppies in groups of at least 5-7. For mixed tanks, maintain 2-3 females per male. For all-male tanks, provide 5-7 males minimum in 20+ gallon tanks with adequate plant cover.
Common Health Issues
Guppies are hardy and less disease-prone than many tropical fish, but three issues are most common.
Ich (White Spot Disease): A parasitic infection causing tiny white spots on body, fins, and gills. You’ll also see excessive rubbing against decorations and rapid gill movement. Prevent it through quarantine (14-30 days for new guppies—they’re often disease carriers from stores), stable temperature (maintain 76-78°F), stress reduction (proper group size and hiding spots), and excellent water quality (0 ammonia/nitrite). Treat by gradually raising temperature to 80-82°F, using ich medication per label instructions, and performing 25% daily water changes. Treatment takes 7-10 days minimum.
Fin Rot: Bacterial infection causing frayed, deteriorating fin edges with white, red, or black discoloration. Prevention is straightforward: maintain excellent water quality with regular water changes, avoid overcrowding, remove sharp decorations, and quarantine new arrivals. Treat with antibiotic medications (Erythromycin or Furan-2), perform 50% water change, and address the root cause (poor water quality or stress). Continue treatment 7-10 days minimum.
Dropsy: Serious internal bacterial infection causing severe body swelling with raised, pinecone-like scales. High mortality rate with extremely poor prognosis. Prevent through excellent water quality, stress reduction, balanced diet, and quarantine. Unfortunately, dropsy is typically incurable once symptoms appear—humanely euthanize to prevent suffering.
Quarantine: Always isolate new guppies (especially store-bought) for 14-30 days before introducing to main tank. Watch for ich (white spots), fin damage, fading color, wasting, abnormal swimming, and lesions. Feed high-quality varied diet during quarantine to boost immune system.
Lighting & Appearance
Light spectrum, intensity, and photoperiod directly affect how your guppies look and behave.
Light Spectrum: Warm white (3000K-4000K) emphasizes reds and oranges, making warm-colored patterns more vivid. Cool white (6500K-7000K) makes blues and metallics glow electric and vibrant. Full-spectrum (5000K-6500K) provides balanced color rendering for both. Many aquarists prefer cool white for the stunning blue effects, but warm white is equally beautiful—experiment and see what appeals to you.
Light Intensity: Moderate to moderately bright (20-40 lumens per liter). Guppies tolerate bright lighting much better than many tropical fish. Unlike blackwater species, they appreciate good lighting that highlights their colors and stimulates natural behavior.
Photoperiod: 8-10 hours daily for most setups maintains biological rhythm and minimizes algae growth. You can extend to 10-12 hours to stimulate breeding activity. Use automatic timers for consistency.
Dark Backgrounds and Substrate: A dark background (black or deep blue) combined with dark substrate makes guppy colors pop dramatically. The contrast between their vibrant coloration and the dark background is stunning. Light substrates wash out colors and reduce visual impact.
Breeding
Guppies are extremely easy to breed, making them perfect for beginners interested in reproduction.
Breeding Method: Guppies are livebearers, meaning females give live birth rather than laying eggs. Eggs are fertilized internally and develop inside the female’s body with a placenta-like connection providing nourishment. Fry are born fully-formed and ready to feed immediately.
Breeding Frequency: With adequate nutrition and males present, females produce live fry approximately every 28 days after reaching maturity. Gestation is 21-30 days (average 22-26 days, shorter in warm water). Females store sperm and can produce multiple batches of fry from a single mating; fry production can continue for months after male separation.
Spawning Triggers: Guppies breed readily with minimal conditions:
- Water temperature of 80-82°F accelerates breeding
- Large water changes (50%) often trigger spawning by simulating wet-season rainfall
- Live foods (baby brine shrimp, daphnia) condition females and increase fry production
- Adequate female-to-male ratio (2-3 females per male or all-female tank) reduces harassment and increases breeding success
Expected Outcomes:
- Fry per Birth: 20-50 average (range 2-200 depending on female age and size)
- Birth Duration: 4-6 hours typically
- Fry Size: Born 0.5-0.75 inches, fully-formed and ready to feed
- Growth Rate: Reach 1 inch in 4-6 weeks with good nutrition
- Sexual Maturity: 8-12 weeks; males develop color and gonopodium earlier
- Fry Feeding: Can eat crushed flakes or powdered fry food immediately; transition to baby brine shrimp by week 2-3
- Feeding Schedule: 4-5 small meals daily initially; reduce to 2-3 times daily by 8 weeks
- Survival Rate (Community Tank): 5-20% (most consumed by parents)
- Survival Rate (Managed): 60-90% in dedicated breeding setups
Natural Breeding (Community Tank): Simply keep males and females together in established tanks. Females will give birth in dense vegetation. Most fry are consumed by adults, but some survive in heavily planted setups.
Intentional Breeding (For Maximum Fry Survival):
- Tank Size: 10-20 gallon breeding tank
- Stocking: 1 male with 2-4 females OR all-female tank
- Substrate: Fine sand or planted bottom
- Plants: Dense Java moss, Ludwigia, Rotala for fry refuge
- Filtration: Gentle sponge filter to avoid sucking up fry
- Water Conditions: pH 7.0-8.0, hard water (12+ dGH), temperature 78-82°F
- Water Changes: 25-30% weekly for normal maintenance; 50% changes stimulate spawning
Population Control: This is the real challenge. Guppies breed so prolifically that population quickly becomes unmanageable. You’ll either need to cull unwanted fry, distribute them to other aquarists, or keep only females. Some breeders use separate birthing tanks, removing gravid females before fry drop, then returning them to the breeding colony.
FAQ
Q: What size tank does a guppy need?
A: The minimum tank size is 10 gallons for 5-7 guppies. However, 20-gallon tanks are strongly recommended for mixed community setups and breeding. Calculate 2 gallons per guppy as a safe minimum. Guppies become stressed in very small tanks and need adequate space for stable parameters and active swimming.
Q: Are guppies good for beginners?
A: Yes, absolutely. Guppies are among the best fish for complete beginners due to extreme hardiness, easy care, adaptability to various water conditions, and peaceful behavior. They tolerate beginner mistakes better than most fish and require only basic equipment—filter, heater, and minimal experience.
Q: How many guppies should you keep together?
A: The absolute minimum is 3-5 guppies. Larger groups (10-15+) display better behavior and reduced stress. The key is male-female ratio: maintain 2-3 females per male to reduce harassment. For all-male tanks, provide 5-7 males minimum in 20+ gallons with adequate plant cover.
Q: What do guppies eat?
A: Guppies are omnivores eating high-quality flakes or micro pellets as staple, supplemented regularly with frozen foods (baby brine shrimp, daphnia, bloodworms) and occasional live foods (microworms, newly hatched brine shrimp). Feed 1-2 times daily. Variety is essential for nutrition, coloration, and immune system support.
Q: What are the ideal water conditions for guppies?
A: Guppies prefer pH 7.0-8.0 (slightly alkaline), hard water (8-30 dGH), and temperature 76-78°F for 2-3 year lifespan. They tolerate pH 6.5-8.5 and temperatures 64-84°F but thrive in optimal ranges. They’re remarkably tolerant of water chemistry variations compared to most tropical fish.
Q: How often do guppies breed and how many fry?
A: Guppies breed approximately every 28 days after reaching maturity. Females give birth to 20-50 fry average (range 2-200). Gestation is 21-30 days. With multiple females in optimal conditions, you can produce 50-100+ fry weekly. Breeding is nearly automatic—controlling overpopulation is usually the challenge.
Conclusion
Guppies are the gateway drug to aquarium keeping. They’re forgiving, colorful, active, and rewarding for beginners while remaining engaging for experienced aquarists. Whether you’re setting up your first aquarium or adding a pop of color to an established community tank, guppies deliver. Males offer stunning visual displays with ornate fins and virtually unlimited color possibilities. Females are productive breeding stock that thrive with minimal intervention. They’re peaceful toward other species, easy to care for, and breed prolifically without requiring any special equipment or expertise. Set them up right—warm, hard, slightly alkaline water; a proper group size with appropriate male-female ratios; adequate plant cover and hiding spots; and regular maintenance—and they’ll reward you with years of color, activity, and entertainment. Once you keep guppies, you’ll understand why they’ve been one of the world’s most popular aquarium fish for over a century.
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Related Guides
- Platy Care Guide: Similar livebearer with comparable care requirements; peaceful community fish.
- Molly Care Guide: Another livebearer with similar breeding and care needs; slightly larger than guppies.
- Endler’s Livebearer Care Guide: Nearly identical to guppies with even easier care; may interbreed.
- Beginner Planted Tank Setup: Step-by-step guide for creating the planted tank guppies thrive in.