Koi Feeding Calculator — Daily Amount by Temperature & Size | Pond Calculator
Free koi feeding calculator. Enter fish count, average length, and water temperature to get the exact daily feed amount and meal schedule.
What this calculator does
Enter fish count, average fish length, and current water temperature. Weight is estimated from length using the standard koi condition factor (K=1/1650≈0.000606), giving realistic values: 12 in → 1.05 lbs, 18 in → 3.53 lbs, 24 in → 8.38 lbs.
How to use
- Feed rate is temperature-driven. Below 50°F (10°C), stop feeding entirely — koi digestion virtually stops and rotting food pollutes water. Optimal range is 68–74°F (20–23°C) at 2% body weight per day, 3 meals.
- Above 82°F (28°C), reduce feeding to 0.5% — warm water holds less oxygen, and heavy feeding stresses fish. Always remove uneaten food after 5 minutes.
Worked Examples
Single koi (1 kg) at 20°C — active growth season
Daily ration = 1 kg × 2.5% = 25 g; split into 2–3 feedings of ~8–12 g each
Feed ~10 g per meal, 2–3 times daily. Remove any uneaten food within 5 minutes to prevent ammonia spikes.
Small pond — 5 koi averaging 500 g each, water at 25°C
Total koi weight = 5 × 0.5 kg = 2.5 kg; daily ration at 3% = 75 g; 3–4 feedings of ~20 g
At 25°C metabolism peaks — increase to 3% and feed 3–4× daily. High-protein (38–40%) pellets support summer growth.
Spring transition — 20 koi averaging 1.5 kg each, water warming from 12°C to 16°C
Total weight = 30 kg; at 12°C stop feeding; at 16°C start wheat-germ pellets at 0.5% = 150 g/day
Begin with wheat-germ once every 2 days at 12–14°C. Increase gradually as water passes 15°C; switch to regular food above 18°C.
Quick Reference
| Below 10°C | Stop feeding — koi digestive system shuts down |
| 10–15°C | Wheat-germ pellets only, every 3–5 days if at all |
| 15–18°C | Wheat-germ once daily, 0.5–1% body weight |
| 18–25°C | Standard pellets, 2–3× daily, 2–3% body weight |
| 25–30°C | High-protein pellets (38–40%), 3–4× daily |
| Above 30°C | Reduce or stop — heat stress impairs digestion |
Common Mistakes
Feeding when water temperature is below 10°C
Koi cannot digest food at low temperatures; undigested food rots in the gut and pond, spiking ammonia and causing bacterial infections
Use a pond thermometer to confirm temperature before every feeding session in autumn and spring
Overfeeding year-round
Excess food decomposes into ammonia and nitrite; chronic overfeeding is the leading cause of poor water quality and koi disease
Apply the 5-minute rule: feed only what koi consume in 5 minutes, then remove the rest
Not transitioning to wheat-germ pellets in autumn
High-protein food is poorly digested below 15°C; undigested protein stresses the liver and kidneys
Switch to wheat-germ (low-protein, easily digestible) once water drops below 18°C and stop entirely below 10°C
Feeding the same amount regardless of season
Summer koi need 3–4% of body weight daily; feeding the same rate in winter when they should not be eating leads to ammonia buildup
Adjust feeding rate monthly based on average water temperature and koi activity level
Note for North American Koi Keepers
In USDA zones 5–6 water temperatures typically drop below 10°C from November through March, meaning koi go 4–5 months without food. ZNA (Zen Nippon Airinkai) North America chapters recommend transitioning to wheat-germ pellets in early October when daytime water temps are still 15–18°C, gradually reducing meal frequency before stopping entirely. Medicated wheat-germ food used as a preventive treatment in early autumn and spring is a common practice in the US koi hobby to reduce bacterial infection risk during seasonal transitions.
Frequently Asked Questions (FAQ)
How much should I feed my koi per day?
Feed 1.5–2% of total fish body weight per day during the optimal range of 68–74°F (20–23°C), split into 3 meals. At cooler temperatures (60–67°F), drop to 1% and 2 meals. Below 50°F (10°C), stop feeding entirely — koi digestion shuts down.
How do I estimate koi weight from length?
A common rule uses a condition factor: weight (lbs) ≈ length (inches)³ ÷ 1650 (K≈0.000606). This gives roughly 1.05 lbs for a 12" koi, 3.53 lbs for 18", and 8.38 lbs for 24". Well-fed koi with a higher condition factor may weigh more.
How many times a day should I feed koi?
At optimal temperatures (68–82°F / 20–28°C), feed 3 times per day. At 60–67°F (15–19°C), feed twice daily. Below 60°F (15°C), once per day is sufficient. Below 50°F (10°C), stop feeding completely until spring.
What happens if I overfeed koi?
Uneaten food decomposes and spikes ammonia and nitrite levels, stressing or killing fish. Overfeeding also contributes to algae blooms by adding excess nutrients. Always remove any uneaten food within 5 minutes of feeding.