What to Feed Koi and Pond Fish: A Canadian Owner's Guide

Feed koi and goldfish a high-quality pelleted staple food sized for their mouths, matched to your water temperature — and only as much as they finish in about five minutes. In Canada, the second half of that sentence matters as much as the first: pond fish are cold-blooded, so the feeding schedule that works in July will actively harm them in October, and once water drops below about 10°C you should stop feeding altogether until spring.

Why water temperature decides what koi eat

Koi and goldfish digest food at the speed their environment allows. In warm summer water their metabolism runs high and they can process protein-rich food quickly. As Canadian water cools through fall, digestion slows dramatically — food sitting half-digested in a cold fish's gut can rot before it's processed, causing serious health problems. That's why the single most useful tool for feeding pond fish in Canada isn't a fancy food; it's a pond thermometer.

The Canadian feeding calendar

Below 10°C (late fall through ice-out): stop feeding entirely. Fish enter a dormant state called torpor, living off body reserves near the pond bottom. Feeding now does harm, not good. This is also the season to make sure the pond has winter oxygen — see our guide to installing a pond de-icer in Ontario.

10–15°C (spring warm-up and fall wind-down): feed lightly — once a day or every other day — with easily digested food. This is the transition zone: watch the forecast, because a cold snap after a heavy feed is exactly the scenario you want to avoid.

15–25°C (the Canadian growing season): this is when koi put on size and colour. Feed a quality staple pellet once or twice daily. Aquascape Premium Staple Fish Food Pellets are formulated for exactly this everyday role, with a balanced protein level for all pond fish.

Above 27°C (heat waves): ease off. Hot water holds less dissolved oxygen, and digestion is oxygen-hungry work. If your pond runs warm in August, feed early in the morning and make sure your aeration system is running — a fountain or aerator is doing its most important work for your fish on the hottest days of the year.

How much and how often should I feed?

The five-minute rule solves most feeding problems: offer only what your fish finish in about five minutes, then net out anything left over. Uneaten food is the number-one avoidable source of pond water problems — it breaks down into ammonia, feeds algae, and adds to the muck layer. Two smaller feedings beat one large one during peak season, and fish that greet you at the surface aren't necessarily hungry; they're trained. A healthy adult koi can comfortably go a week or more without food in summer, and the entire winter without any.

Which food for which fish?

Pellets are the right staple for koi and larger goldfish — they hold together, float where you can see what's eaten, and deliver complete nutrition. For smaller goldfish and young fish with small mouths, premium fish food flakes are easier to take. Treats have a place too: Koi Krunchies are the hand-feeding food that turns koi into pets that eat from your palm — a treat, not a staple, so keep them to a small share of the diet. You'll find the full range in our Fish Food & Care collection.

Feeding and water quality are the same job

Every gram of food you add ends up in the water one way or another. If you're feeding generously, you should also be managing the downstream effects: test for ammonia if fish look stressed after heavy feeding (Aquascape's ammonia neutralizer handles spikes fast), keep beneficial bacteria working on the organic load, and keep water moving. Well-fed fish in still, warm water are the classic setup for a summer fish kill — which is why serious koi keepers treat aeration as fish-care equipment, not decoration.

Fish also need somewhere to feel safe. A shelter like the Aquascape faux log fish cave gives koi and goldfish cover from herons and raccoons and a shaded retreat in heat — stressed fish eat poorly, and predators are a bigger appetite-killer than most owners realize.

Frequently asked questions

Can koi and goldfish eat the same food?

Yes. Quality staple pellets and flakes are formulated for all common pond fish. Match the food size to the smallest mouths in the pond so everyone can feed.

Why can't I feed my fish in winter?

Below about 10°C their digestive system essentially shuts down. Food eaten in cold water can decompose internally before it digests. Your fish are not starving in winter — they're dormant, and this is completely normal for Canadian ponds.

How long can pond fish go without food?

In summer, healthy adult fish are fine for a week or two — a pond produces natural forage like insects and algae. Over winter, they eat nothing at all for months. Vacations are not a feeding emergency.

My fish aren't eating in spring — should I worry?

Check the water temperature first. Appetite returns gradually as water passes 10°C and strengthens through the teens. If water is warm and fish still refuse food, look for stress factors: predators, poor oxygen, or a water-quality issue.

Questions about feeding, fish health, or pond setup? Email info@fountaindepot.com — advice backed by 50+ years of pond and fountain experience in the Greater Toronto Area.