What a koi really costs
Five juvenile koi cost $50–$500, but the pond is the real investment: a 2,000-gallon pond kit with UV, aeration and netting typically runs about $2,900 before digging, stone or labor. Running the pump around the clock is the biggest yearly cost, about $650 at the U.S. average rate with the kit's pump, and with food, a fish-vet house call and medications a typical year comes to about $1,250.
- Life expectancy
- 25–50 years
- Size
- Often 18 in or more as adults; some exceed 3 ft
- Care level
- High
- Price
- $50–$500
- Setup
- About $2,930
- Insurance
- Not offered
Estimate for: Five koi in a DIY-built outdoor liner pond of about 2,000 gallons (11 x 16 ft kit, roughly 400 gallons per fish) with a skimmer, waterfall filter, pump running year-round and a UV clarifier; excavation, stone and labor are not included. Space needed: An outdoor pond with at least 250 gallons per adult koi and more than 2 ft of depth (Angi says 3 ft); five koi need 1,250+ gallons.
Where the money goes each year
A typical year for a koi, with typical spending in an average-cost area.
- Electricity for pump and UV (and winter de-icer)$651
- Aquatic-vet pond checkup (house call)$250
- Illness and injury (average)$180
- Koi pellets$98
- Replacement test kit$36
- Pond water conditioner refill$30
- Typical year$1,250
Most years land between $720 and $2,140. Items replaced on a cycle are spread across the years.
Setup and the first year
For koi, the equipment usually costs far more than the animal.
Getting set up
- Price (koi dealer or pond store, five juveniles)$275
- Pond kit, about 11 x 16 ft (liner, underlayment, skimmer, waterfall filter, pump, plumbing)$2,500
- UV clarifier$240
- Pond air pump kit$45
- Floating de-icer (cold climates)$51
- Pond cover netting$25
- Telescoping pond net$20
- Liquid water test kit$36
- Pond water conditioner (first bottle)$15
- Upfront$3,210
Running costs in year one
- Koi pellets$98
- Pond water conditioner refill$30
- Replacement test kit$36
- Aquatic-vet pond checkup (house call)$250
- Electricity for pump and UV (and winter de-icer)$651
- Illness and injury (average)$180
- Year-one running costs$1,250
First-year total: $4,450.
Make it your estimate
Change the choices that move the price most. Totals update as you go.
$104 a month in a typical year.
- Electricity for pump and UV (and winter de-icer)$651
- Aquatic-vet pond checkup (house call)$250
- Illness and injury (average)$180
- Koi pellets$98
- Replacement test kit$36
- Pond water conditioner refill$30
- Typical year$1,250
What to buy
The gear and supplies in this estimate, matched to a koi. Each link searches Amazon for the right type and size.
- Pond kit, about 11 x 16 ft (liner, underlayment, skimmer, waterfall filter, pump, plumbing)Setup, typically about $2,500See on Amazon
- UV clarifierSetup, typically about $240See on Amazon
- Pond air pump kitSetup, typically about $45See on Amazon
- Floating de-icer (cold climates)Setup, typically about $51See on Amazon
- Pond cover nettingSetup, typically about $25See on Amazon
- Telescoping pond netSetup, typically about $20See on Amazon
- Liquid water test kitSetup, typically about $36See on Amazon
- Pond water conditioner (first bottle)Setup, typically about $15See on Amazon
- Koi pelletsOngoing, typically about $98 a yearSee on Amazon
As an Amazon Associate, PetPriceTag earns from qualifying purchases. Buying through these links costs you nothing extra and never changes our cost figures.
Health costs to plan for
| Condition | What it is | Typical treatment | Cost |
|---|---|---|---|
| Koi herpesvirus (KHV) | A contagious virus causing sunken eyes, extra mucus and sudden deaths; California Fish Vet notes testing is available. Source | No cure; a fish-vet house call ($200–$300) to diagnose and test (lab fees not priced) | $200–$300 |
| Ich and other parasites | PetMD lists parasites among common koi problems; ich shows as white spots, flashing and rapid breathing, and is usually brought in with new fish. Source | Whole-pond treatment (about $180 of API Super Ick Cure for 2,000 gallons) or vet-directed formalin; house call $200–$300 | $180–$480 |
| Egg binding and reproductive tumors | Females can retain eggs, which is often normal, but reproductive tumors can look the same and need surgery. Source | Fish-vet house call to diagnose ($200–$300); surgery costs extra and is not priced | $200–$300 |
The yearly estimate includes an average of $180 for illness and injury. Mainstream U.S. pet insurers do not cover aquarium or pond fish. Nationwide's avian and exotic plan, the main exotic policy, covers birds, rabbits, reptiles, small mammals and a few others, and fish are not among the named species, so budget for medications and the rare fish-vet visit yourself.
What drives the cost
- Size the pond for adult fish. California Fish Vet says at least 250 gallons per koi and deeper than 24 in; PetMD's vet says a small school may need 1,000+ gallons. This estimate assumes five koi in about 2,000 gallons.
- A complete pond kit (liner, underlayment, skimmer, waterfall filter, pump, plumbing) was $1,921–$4,070 at specialist retailers; digging, boulders, gravel and any contractor labor come on top and are not priced here.
- The pump runs 24/7, so its wattage matters more than its price. The Blue Thumb kit's 3,840 gph solids-handling pump draws 380–670 W (about $610–$1,075 a year at the July 2026 U.S. average rate), while a 160 W Aquascape AquaSurge 2000 would cost about $257.
- Vets recommend yearly or twice-yearly aquatic-vet checkups, and koi vets usually come to the pond: California Fish Vet quotes $200–$300 for a house call versus $50–$100 in clinic.
- Koi are a decades-long commitment: PetMD gives 25–50 years, so running costs dwarf the purchase price.
Is it legal where you live?
Koi (Cyprinus carpio) are legal to keep in U.S. ponds and are not on the federal injurious-wildlife list. Never release koi into natural waters, and check your state wildlife agency's rules before moving fish across state lines.
Cities and counties can have their own rules. Check locally before you buy.
- Koi dealer or pond store, five juveniles
- $50–$500
- Lifetime
- $50,500
How this estimate is built
Every line, with the typical, thrifty and generous figures and where each comes from.
More pet fish by yearly cost
- Neon tetras$170 a year
- Freshwater community tank$230 a year
- Angelfish$290 a year
- African cichlids$330 a year
- Clownfish$360 a year
- Oscar$440 a year
- Compare all pet fish
Common questions
How much does a koi cost?
Koi dealer or pond store, five juveniles: $50–$500. The bigger costs come after: about $2,930 to set up, about $4,450 for the whole first year, then about $1,250 a year.
How much does a koi cost per year?
About $1,250 a year ($104 a month) for a typical owner in an average-cost area, ranging from about $720 for a thrifty owner in a lower-cost area to $2,140 for a generous owner in a big city.
How much does a koi cost over its lifetime?
About $50,500 over a 38-year life, in 2026 dollars.
Sources
- PetMD: Koi Fish Care Sheet (Melissa Witherell, DVM)
- California Fish Vet: How to Not Kill Your Koi (250 gal per fish, >24 in deep, yearly UV bulb and test kit)
- Angi: Standard Koi Pond Sizes (about 250 gallons per koi, 3 ft minimum depth)
- California Fish Vet (Jessie Sanders, DVM): Is paying a fish veterinarian worth the cost?
- U.S. EIA Electric Power Monthly: average residential price, July 2026 (18.31 cents/kWh)
- Webb's Water Gardens: Blue Thumb Elite Complete Pond Kit, 11 x 16 ft, ~2,000 gal ($2,499.99; 3,840 gph solids-handling pump, no UV)
- VCA Animal Hospitals: Fish White Spot Disease (Ich)
- Webb's Water Gardens: medium pond kits (Savio 67218 11 x 16 x 1.5 ft, 1,500 gal $1,921.47; Savio PP1526UV with 26 W UV $2,161.84)
- Play It Koi: Aquascape Medium Pond Kit 11 x 16 ft with AquaSurgePRO 2000-4000 pump ($4,070.48)
- Chewy: pond supplies (Tetra Pond AquaSafe 16.9 oz $14.97, telescoping pond net $20.11, Atlantic 10 x 15 ft pond net $24.99, Laguna aeration kit $44.70, Tetra 100-gph air pump $58.49, Tetra 300 W de-icer $51.49, Laguna 315 W de-icer $84.99)
- Chewy: aquarium test kits (API Freshwater and Saltwater Master Test Kits $35.98, API 5-in-1 strips 25 ct $12.98)
- Chewy: koi food (Kaytee Koi's Choice 10 lb $24.90, Mazuri Koi Platinum 20 lb $48.79, Tetra Pond Koi Vibrance 16.5 lb $114.97)
- Play It Koi: Blue Thumb solids-handling pumps (3,840 gph, 380–670 W)
- Aquascape: AquaSurge 2000 Pond Pump (2,000 gph, 160 W, $439.99)
- Chewy: API Liquid Super Ick Cure (4 oz $6.99, 16 oz $21.19; 5 ml per 5 gal, repeat after 48 h)
- eCFR: 50 CFR 16.13, injurious fish, mollusks and crustaceans
Estimates in 2026 US dollars. Vet prices for this pet use the same region adjustment as the rest of the site (methodology). Updated October 15, 2026. Spot a wrong figure?