Preparing Your Koi Pond for Fall

As the days grow shorter and cooler, koi ponds begin a natural shift. Fall is one of the most important transition times of the year—not just for your pond’s ecosystem, but for your koi themselves. Taking a few key steps now will help keep your fish healthy, your water balanced, and your stress low as the seasons change.

Why Fall Preparation Matters

Koi are cold-blooded animals, which means their metabolism slows down as water temperatures drop. During fall, koi begin storing energy for the winter ahead. Their digestion changes, their activity levels drop, and your pond’s ecosystem becomes more sensitive.

If you don’t make seasonal adjustments, koi can become stressed, sick, or even vulnerable to serious issues like ulcers, sores, or pH crashes. That’s why proactive care in fall makes such a difference for long-term koi health.

The Most Important Fall Pond Care Steps

1. Check Water Temperature Often

Once your pond is consistently below 15°C (59°F), koi begin slowing down. Feeding, filtration, and water chemistry all need to adjust.

2. Switch to Wheat Germ Food

As koi digestion slows, their ability to process protein-rich food declines. A wheat germ-based diet helps them transition smoothly into winter.

👉 Many koi keepers use a seasonal food like Nijikawa Four Seasons to support digestion and energy through fall.

3. Maintain Your KH (Carbonate Hardness)

One of the most important — and often overlooked — fall priorities is keeping your KH between 100–150 ppm.

In fall, heavy rain adds highly acidic water to your pond. This can rapidly lower KH, which stabilizes your pH.

A low KH means an unstable pH — and if your pond has a pH crash, all your fish could die.

Even if they survive, they’ll be stressed. Stressed koi may flash, scrape their sides, and break skin—opening the door to infection and ulcers.

👉 Regularly test KH and buffer your water as needed. Stable water = healthy koi.

4. Remove Debris Frequently

Falling leaves and organic waste cause ammonia spikes, reduce oxygen, and feed unwanted algae. Use a net or skimmer daily and consider a pond cover if you’re in a high-leaf area.

5. Check Filtration and Aeration

Your filters may need less work in fall, but oxygen is still vital. Keep aerators running and monitor flow to ensure it’s not reduced by clogging or debris.

6. Observe Fish Health Carefully

Now is the time to catch issues early. Look for flashing, clamped fins, bottom sitting, or red patches. Parasites and minor wounds are easier to treat before winter sets in.

Fall Prep = Healthier Fish, Less Stress

The goal isn’t just survival—it’s for your koi to go into winter calm, strong, and healthy. Fall preparation gives you peace of mind and gives your fish the best chance for a smooth season.

And remember: Robert’s Koi Farm is only open for two more weeks this season.

Now’s the time to stock up on koi food, get advice, or pick out that one special fish before winter sets in.

📍 Robert’s Koi Farm – Fort Langley, BC

Healthy koi raised in natural clay mud ponds.

📦 Shipping available across Canada