Every koi is a stack of tissues that must agree under season, prey and human pressure.
Meters below repeat the six atlas scores as gauges; they are relative marks, not laboratory certificates.
Systems
Support and integument
A heavy-bodied cyprinid with barbels and a pharyngeal mill. Ornamental lines select skin cells, not wild streamlining.
Feeding apparatus
Omnivorous pond browsing -- pellets, plants, invertebrates. Winter metabolism drops in unheated outdoor ponds. The feeding kit sets the ecological-role score relative to the other 23 types.
Respiration and circulation
Gas exchange and blood flow are tuned to the koi energy budget -- dive, hover, sprint or bulk browse -- not to a generic vertebrate template.
Senses and neural control
Taste barbels and a lateral line in still water. Show judging is a human sense laid over the fish.
Reproduction and ontogeny
Replacement rate is the hidden resilience number. KHV, poor water, and escape into wild basins. A champion pattern does not confer disease immunity.
Thermoregulation and salt/water
Climate and osmoregulation bound where a koi can close its daily budget. Field sites in the English-speaking world still measure that envelope first.
Relative meters
Hotspots
Primary weapon or tool
The bill, teeth, trunk, pouch or talon that field guides name first -- and that trade or conflict usually targets.
Energy store
Fat, cache, crop or bamboo hours that decide whether a season closes.
Natal or breeding site
A redd, eyrie, den, anemone or ice lair -- often a single-point risk (Izumi, Natron, Gir).
Sensory organ
Taste barbels and a lateral line in still water. Show judging is a human sense laid over the fish.
Human interface
Hunt, tourism, film or quota -- the surface where koi biology meets English-language law.
Tissues & materials
Keratin and integument
Feathers, fur, baleen or skin plates -- tissues, not metals. Moult and wear are the maintenance cycle.
Bone and cartilage
Load paths for stoop, lunge, knuckle-walk or hover. Marrow and pneumatic bone differ by family.
Muscle and tendon
The expensive tissue that speed and intelligence scores only hint at.
Fat, oil and glycogen
Stores that migration, fast and lactation spend. A market for those stores (oil, ivory, fin) is a historical threat.
Keep exploring
More in Fish
Great white shark
Apex lamnid whose warm muscle, broad diet and 1975 cinema still outrun the tagging papers.
Overall 66 🐟Salmon
Anadromous fishes that move ocean fat onto spawning gravels -- and into forests, treaties and hydropower fights.
Overall 63 🐟Atlantic bluefin tuna
A warm-bodied tuna whose Tokyo auction prices and ICCAT quotas made a single fish into a geopolitical unit.
Overall 54 🐠Clownfish
Anemone-dwelling damselfish whose 2003 film fame became a capture-and-reef case study.
Overall 41 🐴Seahorse
Upright syngnathids whose male pregnancy and dried-medicine trade made a small fish a CITES case.
Overall 28 🐡Pufferfish
Beak-toothed inflators whose tetrodotoxin made a Japanese cuisine and a genome project out of one family.
Overall 41 ⚡Electric eel
Amazon knifefishes whose stacked electrocytes taught Humboldt, Volta arguments and a 2019 species split.
Overall 36