Overview
The Koi (Cyprinus carpio) is a freshwater fish belonging to the family Cyprinidae. It thrives at temperatures of 10–25 °C with a pH of 6.5–8.5, and requires a minimum tank volume of 2000 litres. Known for its peaceful pond fish; social and inquisitive, it is considered a intermediate-level species. Pond fish not suited to aquariums; can recognise individual keepers and eat from the hand. Water changes of 25–30 % weekly, stable parameters, and appropriate tank mates are key to long-term success with this species.
Scientific Classification
| Rank | Classification |
|---|---|
| Family | Cyprinidae |
| Genus | Cyprinus |
| Species | Cyprinus carpio |
| Water type | freshwater |
| Native range | Reunion|Europe & Northern Asia (excluding China)|Middle America|North America|Oceania|Baltic Sea|Westerschelde|North West Atlantic|Europe|Zeeschelde|Black Sea|Gulf of Saint Lawrence|North Pacific Ocean |
Natural Habitat
Cyprinus carpio originates from Reunion|Europe & Northern Asia (excluding China)|Middle America|North America|Oceania|Baltic Sea|Westerschelde|North Wes. It inhabits freshwater environments and is adapted to the water conditions found in its native range.
Appearance
Adults reach 50–90 cm in length. The body is freshwater and the species displays characteristic coloration suited to its environment.
Behavior
This species is described as a peaceful pond fish; social and inquisitive. It does not school and can be kept individually or in small numbers. Activity level is moderate. Pond fish not suited to aquariums; can recognise individual keepers and eat from the hand.
| Trait | Value |
|---|---|
| Temperament | peaceful pond fish; social and inquisitive |
| Schooling | No |
| Activity level | moderate |
Water Requirements
| Parameter | Ideal Range | Notes |
|---|---|---|
| Temperature | 10–25°C (50–77°F) | Use a reliable adjustable heater |
| pH | 6.5–8.5 | Avoid sudden swings |
| Hardness (GH) | 8–25 dGH dGH | Soft to moderately hard |
| Ammonia | 0 ppm | Any detectable ammonia signals a problem |
| Nitrite | 0 ppm | Toxic even at low levels |
| Nitrate | <20 ppm | Manage through regular partial water changes |
| Min. tank | 2000L (528 gal) | Larger tanks are easier to keep stable |
Interesting Facts
- Koi were selectively bred from common carp in Japan during the 1820s for their ornamental colours.
- Champion Koi have sold for over $2 million USD at auction, making them among the world's most expensive fish.
- Koi can live over 35 years; the oldest recorded Koi, 'Hanako', was 226 years old.
📋 Full Care Guide
Ready to set up a tank for your Koi? The complete care guide covers tank setup, feeding schedule, common diseases, tank mates, and breeding.
Read Koi Care Guide →Related Species
Related Species & Guides
This species profile was reviewed for biological accuracy and practical aquarium care guidance. For suspected illness or disease, test your water parameters first and consult an aquatic veterinarian if symptoms persist.