Don't worry about the air temperature. Keep an eye on the pond temperature and once it starts to stay below 50�, stop feeding them.

An aquarium thermometer is quite inexpensive at Walmart. I quit feeding when the water temperature did not get to 50�F.

Also make sure you are feeding them a food with a high content of wheatgerm, as their digestive systems are slowing down now.

I read somewhere the other day to feed them cheerios when pond temp drop.Its the same as koi food with the wheatgerm.

My pond temp is 58 degrees too. I am feeding a wheat germ based Koi food and will feed till water temps get around 50 and as long as the Koi want to eat.

Also-bulldinkie Cheerios is not as good as a high quality Koi food. Compare the labels and you will see the difference.

Regards,
Lisa

I'm currently feeding my goldfish Tetra Spring & Fall Diet. They recommend it for temperatures down to 39 degrees F. Their staple food for summer is only for temperatures above 50 degrees.

Pond fish foods generally include temperature guidelines in their labeling.

This doesn't mean you have to feed when temps are in the 40's, but if the food is labeled for it, you probably can. You'll want to feed smaller quantities as appetites slow down.

Goldfish and koi are not the same fish. They are close but not the same. The common goldfish is a true cold water fish and it could eat all winter without a problem. Koi are not and could have a problem during the winter eating. To play it safe you should stop feeding when the water temperature drops below 50. Can they eat at a lower temperature? Yes as long as the temperature doesn't drop below 40 the fish will be fine.
Lisa your not feeding Cheerios because they are a good food but because it is very low in protein so very little ammonia and are high in carbs. Carbs are easily and quickly used by the body. Proteins that the body a long time to convert them to energy. Would I feed Cheerios to the fish all the time? No. But at the end of the season or the beginning food yes. Also a good food when overfeeding the fish such as when you are showing the fish off when a lot of company is visiting such as a pond tour.
Mike

Mike makes a good point about koi being more sensitive than goldfish. Since the original poster was asking about goldfish, I just gave the straight dope from my fish food bag. Interestingly, Tetra markets this food for all pond fish, including koi, and includes no special directions for them. I hate seeing all the disposable koi in the pet store tanks every spring. Garden centers put big koi in little display ponds and give people wrong ideas about them. I'll stick with my beautiful, hardy goldfish, thank you very much.

Our humble 5-cent comets give us a lot of pleasure.;-)

One of the biggest reasons to stop feeding fish (koi AND goldfish) below 50ð is that the beneficial bacteria in the bio filter can't handle it. At cool temps, that bacteria is not capable of performing it's job....converting ammonia to nitrite and then to less harmful nitrate. If you feed and the filter can't handle it, the water quality will begin to suffer.

so you see it really does not matter which species we are talking about, the limiting factor is the filter bacteria which is the same regardless of the fish species.

That's a good point.

Bacterial activity occurs between 5 degrees C and 30 C, with the most activity at 30 c. With temperatures above 30 c, the bacteria will start to die off.

http://www.shortypen.com/projects/pond/design/index.htm

5 C is about 40 F, so bacterial activity is very sluggish in the 40's. Fish metabolism is slower too, so they are most likely producing less ammonia. I guess those of us feeding below 50ð would do well to watch our ammonia and nitrite.

Regarding Cheerios. Mike- I would have no problem feeding my fish Cheerios for a week or so in the spring or fall until I obtained or made some good Koi food. Spring and Fall are at least 6 weeks each in zone 5. I would not feed them Cheerios for 3 months of the year though since they fast for 6 months. I think we both agree that Cheerios is fine short term. Thanks for the response.

Cheerios was for short term,When temps drop you can use cheerios,