Live on Ethereum
Grow your eternal koi
Onchain Koi is a fully onchain collection that grows in real time based on a real koi's life cycle, using each token's mint timestamp as its birth time.
3.25 ETH
Total volume
2,949
Koi keepers
0.00035 ETH
Floor price
Featured ponds
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Top 10 koi keepers
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They grow with you
Each koi starts from its mint timestamp. The token uses real elapsed time to move from egg, to fry, to fingerling, to juvenile, and finally adult. Growing in real time with your human clock.
const DAY = 24 * 60 * 60;
function koiAge(mintTimestamp) {
const ageDays = Math.floor((Date.now() / 1000 - mintTimestamp) / DAY);
if (ageDays < 5) return "Egg";
if (ageDays < 28) return "Fry";
if (ageDays < 183) return "Fingerling";
if (ageDays < 730) return "Juvenile";
return "Adult";
}Koi life cycle
The Egg Stage:
Day 1 to Day 5
Spawned in the spring when water temperatures hit around 65°F to 70°F (18°C to 21°C), a single female can release hundreds of thousands of sticky eggs. They cling to pond plants and rocks. The translucent eggs incubate for roughly 3 to 7 days depending on water warmth. Sadly, they are a delicacy in the pond — adult koi (including the parents) will readily eat them if they aren't protected.
The Fry Stage:
Week 1 to Week 4
When they first hatch, they are called fry and are only about 5 millimeters long.
First 2-3 Days: They cannot swim well and have no developed mouth. They use a tiny sticky pad on their head to attach to plants and survive entirely on their remaining yolk sac.
Free-Swimming: Once the yolk is gone, their swim bladder inflates, and they rise to the surface to gulp air. They start hunting microscopic nutrients like algae and rotifers.
First 2-3 Days: They cannot swim well and have no developed mouth. They use a tiny sticky pad on their head to attach to plants and survive entirely on their remaining yolk sac.
Free-Swimming: Once the yolk is gone, their swim bladder inflates, and they rise to the surface to gulp air. They start hunting microscopic nutrients like algae and rotifers.
The Fingerling Stage:
Month 1 to Month 6
Once they reach about 1 inch (2.5 cm) in length, they look like miniature fish and are called fingerlings. This is a thrilling stage because their scales form, and their distinct colors and patterns finally begin to show. They grow incredibly fast during these months, switching to a diet of small insects, larvae, and crushed koi pellets.
The Juvenile Stage:
Month 6 to Year 2
At this point, the koi are growing at a rate of roughly 0.5 to 1 inch per month. They are strong, agile, and highly active. While they look like miniature adults, they are putting all of their metabolic energy into frame development and structural growth rather than reproduction.
Adult & Mature Koi:
Year 2 to Year 3+
Koi reach sexual maturity around age 2 to 3 for males, and age 3 to 4 for females. They are typically 10 to 12 inches long at maturity, but they won't stop growing there. A well-cared-for adult koi can comfortably reach 24 to 36 inches in length.
Gotta catch 'em all
more than 12k combination
FAQ
Is the NFT fully onchain?
Yes. The token metadata and SVG image are generated by smart contracts on Ethereum. The koi can be read directly from the chain without relying on IPFS or a centralized image server.
How does the koi grow?
Each token uses its mint timestamp as its birth time. The contract compares that timestamp with the current block time to determine whether the koi is an egg, fry, fingerling, juvenile, or adult.
Does the image update automatically?
Yes. The onchain renderer calculates the current age whenever tokenURI is read. Marketplaces and wallets may cache the image, but refreshing metadata will pull the latest onchain state.
Can I make it grow faster?
No. Growth follows real elapsed time from the token birth timestamp. The waiting is part of the work: patience is the mechanic.
Is there a roadmap?
Onchain Koi can develop into lots of render possibilities, from interactive ponds to 3D voxel koi, generative worlds, and future experiments built from the same onchain traits and growth system.