Koi still come to the edge of the pond, but they take longer to eat. Should you keep the summer ration, switch to Wheat-Germ, or stop feeding altogether? In autumn, the best guide is the water temperature, combined with observation of the fish and the food’s instructions.
Wheat-Germ is primarily used to adapt feeding to cool periods. It is not intended for feeding inactive fish at just any temperature. For koi and goldfish overwintering in an outdoor pond, food intake should be reduced as temperatures drop, and then suspended when conditions no longer allow for appropriate feeding.
Why do fish eat less when the water cools down?
Water temperature influences fish physiology, particularly their activity and digestion. The Merck Veterinary Manual notes that feeding methods vary based on species, age, farming system, and temperature. Therefore, an appropriate ration during a summer growth period does not automatically remain suitable in November.
The change also concerns the pond. Any uneaten food will eventually degrade, while ingested food contributes to waste that the filtration system must manage. Reducing the ration when demand drops helps avoid unnecessary inputs.
Observe the group without focusing only on the greediest fish. Some quickly take the pellets while others remain at a distance. This difference helps in deciding the quantity, pellet size, and where to distribute the food.
Measure the water before choosing the meal
The weather forecast provides air temperature. Fish, however, live in the water, which can change differently throughout the day. Use a thermometer and take your measurements under comparable conditions, at a depth representative of their living zone.
During the autumn transition, record several values over a few days. Water that remains cool does not call for the same decision as a temporarily milder temperature in the mid-afternoon. A very simple notebook is enough: date, temperature, food type, amount offered, and amount actually eaten.
If you use an automatic feeder, check its settings before the fish slow down significantly. Switching to a seasonal food does not, by itself, change the number of feedings. Also, test the amount actually released: it can vary with pellet size.
When to switch to Aquifood Wheat-Germ?
Wheat germ is "germe de blé" in French. In fish feed, this term refers to formulas containing this ingredient, often offered for their digestibility during cool periods. It does not describe a single recipe common to all brands.
The product sheet for Aquifood 3 mm Floating Wheat-Germ specifically targets koi in spring and autumn, and advises introducing it when the water temperature drops below 15°C. Use this benchmark along with fish activity levels and the instructions on the packaging you possess.
Plan the transition before you have a large stock of summer food to finish. Start with small distributions and observe how they accept it. The benefit of a suitable food never exempts you from adjusting the quantities.
Also, avoid presenting Wheat-Germ as a guaranteed protection against diseases. A balanced diet contributes to fish maintenance, but it does not correct poor water quality or an ailment that requires a diagnosis.
At what temperature should you stop feeding?
There is no single threshold applicable to all species, all formulas, and all ponds. In its seasonal advice, Aquiflor provides a stop benchmark of approximately 6°C for relevant pond fish, noting that sturgeon require different management.
Manufacturers may publish other guidelines for their own foods. For comparison, Hikari indicates not to distribute its Wheat-Germ formula for koi below 5°C. This value pertains to that product: it does not automatically define the minimum temperature for Aquifood or another food.
Above all, remember this: the 15°C transition benchmark does not mean "feed until 0°C." As the water cools, reduce the ration, respect the threshold specified by the food, and stop offering food to fish that are no longer eating. If in doubt about a product, have its usage limit confirmed.
| Situation | Practical decision |
|---|---|
| Water cooling, koi still active, approaching 15°C | Prepare for the switch to a suitable transition formula and reduce intake based on appetite |
| Cool water within the range allowed by the food | Small, monitored distributions, with no leftovers |
| Temperature below the product's limit | Stop this food according to the manufacturer's instructions |
| Fish refusing food | Do not persist; observe and check water quality if the change is unusual |
| Heated pond or species with special needs | Follow a program specific to the system and the fish |
How to reduce quantities without feeding randomly?
Prepare a small dose, distribute it gradually, and see what happens. If the fish take the first few pellets and then turn away, stop. A handful poured all at once provides less control and may leave leftovers in the corners of the pond.
Hikari recommends, for its cool-water programs, to take activity into account and favor the mildest part of the day when the temperature varies. This observation principle is useful, but the frequencies indicated on one formula should not be copied onto another.
Use a small measuring scoop reserved for the food. This will allow you to reduce portions in a reproducible way and clearly explain the routine to someone replacing you. "Half a scoop if the fish are eating actively" is more precise than "a small handful as usual," provided that this distribution remains authorized by the instructions and the temperature.
Floating, sinking, and pellet size: choosing based on the fish
A floating food makes it easier to observe intake and remove leftovers. However, it must correspond to the feeding behavior of the fish. The Merck Veterinary Manual stresses the importance of choosing food adapted to their habitual feeding zone.
With a 3 mm pellet, observe in particular if the fish take it easily. A size that is too large or a distribution dominated by a few individuals can complicate mealtime. The size of the packaging also matters: choose a quantity that you can store correctly and use within the indicated timeframes.
Reseal the package, keep it dry, and note its opening date. Do not use food that shows mold or obvious signs of deterioration. Buying a large bucket for a few weeks of transition is not always the most practical choice.
What to do during a mid-winter thaw?
A sunny day may tempt you to resume feeding as soon as the fish move more. Measure the water first, observe its trend, and verify that the distribution is compatible with the food. The temperature felt on the patio is not enough.
If conditions truly allow for a resumption, offer a very small amount under supervision. Do not try to compensate for several weeks without feeding with a large meal. In an unheated outdoor pond, rapid variations require more caution than just reading an isolated threshold.
In the spring, the resumption should also be gradual. Appetite may increase while the filtration capacity has not yet caught up. Continue to check the water, especially if the filter has been stopped, cleaned, or disturbed.
If the fish stop eating, is it necessarily the cold?
A steady decline in appetite with cooling water can be expected. A sudden refusal, accompanied by rapid breathing, rubbing, loss of balance, or unusual behavior, merits verification.
Check the filtration system and available parameters. The JBL ProAquaTest CombiSet for ponds is useful for tracking pH, KH, ammonia, and nitrites. It does not measure all parameters, including dissolved oxygen.
The UF/IFAS advises reducing or suspending feeding during an ammonia issue, then correcting the system conditions. Adding a product or changing food without identifying the cause can delay the correct intervention. If the signs persist, seek competent advice regarding fish health.
The most common mistakes to avoid
- Continuing summer rations because the bucket is not empty.
- Replacing food without reviewing the automatic feeder settings.
- Using air temperature to decide on feeding.
- Applying the Wheat-Germ threshold to all formulas.
- Feeding more after a period of cessation to "catch up."
- Applying the same rules to koi, goldfish, and sturgeon.
A good routine comes down to a few actions: measuring, observing, distributing small amounts when conditions allow, removing leftovers, and noting changes. This follow-up is much more helpful than having the same stop date every year.
Preparing for the food transition
For your koi still active in spring or autumn, compare pellet sizes and usage conditions. Keep the thermometer and observation at the heart of your decision-making.
Sources
- Aquishop — Aquifood 3 mm Wheat-Germ: seasonal purpose and introduction benchmark.
- Aquiflor — Feeding Advice: seasonal benchmarks and sturgeon cases.
- Hikari — Wheat-Germ Formula for koi: example of formula-specific instructions.
- Hikari — Feeding your coldwater fish: appetite, temperature, and gradual resumption.
- Merck Veterinary Manual — Providing a Home for Fish: dietary needs and food selection.
- UF/IFAS — Ammonia in Aquatic Systems: feeding and ammonia problems.
