I always believed that during hot summer months you should feed koi much more and more frequently. They are more active and grow faster. They will need more protein to compensate for the extra energy being used.

In the latest (December) issue of KOISA, an article suggested that you should refrain from feeding a lot during hot summer days, and even stop feeding when it is very hot.

What is your opinion?

the biggest bull I ever heard, if you filtration and aeration are sufficient then feed, feed, feed.

What was meant by hot in this article?

I believe that there is merit in being careful of the feed rate at high temperatures. This website http://www.majestickoi.com/cat1.html suggest to stop feeding at 85 degrees, assume Fahrenheit, which translate to 29,4 Celsius.

Also see;
http://waterontheweb.org/under/waterquality/oxygen.html
http://www.engineeringtoolbox.com/oxygen-solubility-water-d_841.html

When considering this topic bear in mind that the amount of dissolved oxygen DO in water reduces with increased temperature. In fact at some temperature level the DO potential of water is in fact lower than what the Koi need, irrespective of the aeration of the pond. This threatening DO temperature is probably higher that what the Koi can tolerate and they will be dead before this mysterious level is reached. Nevertheless oxygen is consumed by not only the over the limit number of Koi in the pond but also algae, plants, bacteria in the bio filter and those thriving on the dirt in the mechanical filter, the list goes on.

Al of these factors combined contributes to the reduction of the lethal temperature level. To make things worst during this whole process; feeding the Koi increase the amount of ammonia in the water adding to the threats to Koi survival.

After all said it does seem to make sense to be observant of Koi behaviour and the feed rate when water temperature increase.

I wonder if the lethal temperature level is in reality a threat to us and if, with good filter systems and aeration in our ponds, we will easily reach that level. My pond’s water temperature is now 22 Celsius which I believe is well below the threatening level. As a result I will rather concentrate on the other boggy men and Tokolosh that is abound at all Koi ponds!

Hi,

The article was by Ray Jordan (a member of this forum) maybe he could answer for himself!

In my young days when I still needed to find a mate on of my objects of my desires was the daughter of an ictologist, jeez I may have it wrong but in anycase he was a fish guru with the old Transvaal Department of Fisheries.

I spent many hours over weekends with him in his lab near Marble Hall and he told me this ...

Every fish specie has a top and bottom critical temperature ... it is a temperature where the fish's metabolism changes dramatically. On the bottom side you reach a temperature at which the population will naturally stop feeding and then if the temperature drop further you reach a point where 80% of the population dies ... the vast annual kurper deaths in the Transvaal is evidence of this.

In a pond the water temperature will drop down but due to size of the waterbody the sun will heat the water up in the day and make the water body temp of the pond rise more than what would happen in big natural body of water. The danger is when this seesaw happens over the boundery where the fish would naturally stop feeding. It will feed duringthe warmer part of the day but then at night the temp drops. As the temp drop to and below that species critical temp the metabolism slows down to a mere trickle and food does not get processed fast enough in the gut. This can lead to the food actually rotting and causing massive bacterial infections that could perforate the gut.

SO his advice to me was that pond fish needs to go on a fast during the months without "R"'s in it's name.

Another issue is that during summer fish would feed heavily and build size and weight but by late season they begin to store large quantities of body fat. This what the fish will live on during the fasting period. He had the theory that if you need good shape in your fish you need to ensure that it burns all the stored fat off during the fast before the next growth season starts. Al residu fat from the previous season will get trapped beneath layer of new growth muscle and this trapped fat will get hard and as the end of season fat layer is laid down the fish will begin to go out of shape.

Prolonged residual fat layers will result in a awkwardly shaped fish.

It must be noted that he did not speak to me specifically about koi but the species he worked with was Barbel, kurpers, yellowfish, carp and bass.

The kurpers was the most sensitive to temperature drops of all 5 species.

On the upper temperature limit he was of the opinion that the fish would naturally stop feeding if conditions were stressful. So a poster above mentioned that proper water management negates this hot weather feeding issue and my almost father in law seems to agree with that.

He also showed me that carp that got as much food as it wanted would go from fingerling to 1.5kg in year one ... reach 3 kg in year two and six kg in year 3. Some posts in the Grow Threads seems to echo this.

Now I am talking about info I gathered in 1978 ... so I may be off a gram or two in any direction.

For next 6 weeks I will be feeding my koi quite heavily and then in May I stop as soon as the water begins to cool off sharply. I only strt feeding again in late August.

Athough I am now only in year two of my ponds my fish is for sure not show quality as far as colours is concerned but in general I have fish that are well shaped.

This is all I can say on this topic of hot weather. I will test the temp tomorrow but since December the water temp is round the 30 C mark with some days higher and my fish does not appear to be stressed.

That was an interesting post Colyn,

Temp and Feeding Koi:

The way I look at it is slightly differently.

Koi (coloured carp) are basically warm water fish as opposed to trout which are cold water fish. So koi tolerate a wide range of temperatures very well. Koi do not like to be at low temperature for long periods of time. Low meaning water temperatures of 10C and below. Whereas trout thrive in these conditions.

So the winter temperatures found in Europe, Japan and some parts of America place an enormous stress on koi because these low temperatures last for months.

In South Africa our winter temperatures are a) not as cold as these countries and b) do not last as long. Up here on the highveld the coldest time of the year only lasts for a few weeks not three or so months as in England. So it is not that common to get pond water temperatures below 10C for a long time.

On the other side of the scale when we refer to hot temperatures we must always refer to the temperature of the pond water. I should imagine that 80 - 90% of ponds have some sort of a waterfall. A waterfall has a cooling effect on the pond water. So the chances of pond water temps reaching unacceptable levels are very remote.

The oxygen carrying capacity of water decreases as temperatures rise BUT to what – at a water temperature of 30C the maximum amount of oxygen that can be dissolved into water is around 6.2ppm. Not fantastic but still very acceptable and way above the unacceptable low range of 4 – 5ppm. I wonder how many ponds out there do actually have an oxygen level of 6.2 ppm at normal temperatures.

So at a water temperature of 30C – again not that many ponds with a water temperature of 30C – there is quite enough oxygen to continue to feed normally – or because the temps are high then feed well.

Now as temperature decrees in autumn do not stop feeding. This is critical. Provided the water temperatures are decreasing gradually, which they will do under normal circumstances, you continue to feed. You will notice that as temperatures get down below 15C or so the koi do not eat so much. So you feed less. At around 12C you should be feeding even less. Below 10C your koi collection will not have much appetite so a small feed every second day should be quite enough.

What you will be watching out for in winter is cold fronts where a pond could drop more than 5C over night. You simply stop feeding until temperatures rise and stabilise.

I honestly believe that not feeding between May and August is very harsh on the fish. In May and even June water temperatures are still very good. Only around about 12C is the metabolism slowing down to a low level where a minimum amount of food is needed. But so long as the koi is swimming and breathing it needs energy for metabolism and nutrition for maintenance of its basic bodily functions.

One further point even at low water temperatures our koi need their immune systems to fight infections - all the time. The immune system needs a host of trace elements, etc to keep it functioning. It would not be prudent to starve to immune system of what it needs.

Yes I do agree with Colyn about large fluctuations in temperature. The koi battle to adjust rapidly to large temp fluctuations - especially at colder temperatures. This is not an every day occurance and shoud it happen (after a hail storm or something like that) then you stop feeding for a day or two.

Chris

Hi Chris

I agree with most that you are saying but I am not so sure about your feeling that koi does not like low temperatures.

In the wild fish feed on what is available and the stuff koi eats do get dramatically less during winter. However ... ask any carp angler and he will tell you that it is in that cold nasty windy hellish nights that you catch the biggest ones

As I have said ... the fasting period is to allow the builtup fat to be utilised.

Here is my personal experience.

I use a koi feeder to feed my koi and they usually get fed 6-8 times a day in summer and as we move into winter i will take 2 feedings way from them for every 2'C that the temp drops below 22'C. It will be the latest feeding in the evening and the earliest feeding in the morning that will be taken away. I feed 35g of food per feeding.

In the temps of 22-24'C the kois where hungry all the time...

As we moved into January the water was 24-26'C and i noticed that my kois did not want to eat between 11am and 15pm and they left the pellets on the surface while they stayed very deep down in the pond. So i came to the conclusion that the direct sun on my pond must be what is stopping them from feeding at those hours.

I then moved my feeding times into the evening and very early morning leaving the kois to "relax" during the direct sun in the day. And they fed 300% beter. They where very active and hungry in the eveneings and I even gave them more to eat at those times than what the feeder gave them.

Two weeks ago thats now Feb my water tempreture moved into the 27-28'C area and they suddenly "lost their appetite" I would come out in the morning and find the majority of pellets from the 4am, 6am and 8am feeding in the surface skimmer. So i reduced the feedings to only at 4am and 8am but they still left some over... What was going on? In the evenings they where not as active anymore and did not eat that well eather.

In the week that just passed we had very very warm days reaching 42.5'C during those days my water temp was sitting at 28'C constantly in the day and at night and it was theatning to go over to 29'C. There was 3 days in that time period that my kois ate nothing! The pellets where there but they could not be bothered. In the evenings i would come outside as usual to sit next to my pond and they would be 2.5-3m down which was unusual.

In the last 3 days from now the water tempreture has dropped back down to 26-27'C and the kois have started to eat like normal again and they are actually hungry again and waiting underneath the feeder at feedng times.

This is just something i have noticed personally. The fact that the koi feeder gives them exactly the same amount of food to eat per feeding made it very easy to see how tempreture affected them.

Above 26-27C water temp my Koi dictate the amount of feeding, when temp cool off we are back to normal.

My pond is in full sun and I have the same problem in very hot weather. They are deep down and swim next to the side of the pond in the shady area, or under the bridge. Not in mood to eat to much untill later the afternoon

Hi Colyn,
I consider low temps to be 8C and less.

Fishermen catch the biggest carp in the coldest times because the fish just wants get as far away from the cold water as possible so hitching a lift on a fishing rod is a good idea.

Hi Wayne, Hi Marius

With regards koi not eating at high temps I have a question -

We know that koi do not tolerate large changes very well and their body take time to adjust. This applies to rising temperatures as much as it applies to decreasing temperatures.

We know than when a pond suddenly drops in temp koi become less interested in their surroundings and eat less. But a few days later, after the body has adapted, they return to normal feeding and behaviour.

This would apply to sudden rises of a few degrees as well.

The question is - at "high" temperatures when the koi were observed to go off their food a little - was it a sudden rise in temp or a gradual rise in tem.

If it were a sudden rise in temp then that completely understandable as the koi take time to adjust. A gradual rise in temp over few days then that is a different matter.

I also noted that the fish never actually went off the food only during the middle of the day did they seem to go off feeding. I always fed in the morning and in the evenings. I only feed at mid day in mid winter.

Interesting.

Chris

Hi Chris

Quote:

In the week that just passed we had very very warm days reaching 42.5'C during those days my water temp was sitting at 28'C constantly in the day and at night and it was theatning to go over to 29'C. There was 3 days in that time period that my kois ate nothing!

Sudden change of the outside tempreture for sure...but the water temp did not change with more than 2'C degrees daily but if you look over the weekly period the temp did go up with about 4'C in my pond in the last 3 weeks.. The outside tempreture was extreme and the humidity very high. Usually the water get slightly colder during the nights and rop with 1'C but not in that week.

Ernst also experienced the same problem and also feed at night now due to the koi not being hungry during the day.

Koi definitely eat better in the early mornings and evening.

I have a waterfall, air diffuser, vernturi, a external vernturi and air in my moving bed filters that pounds the water...so i doubt if it could have been a oxygen problem. I tested my dissolved oxygen levels last year at roughly the same time and at 25'C i hade a dissolved oxygen level of 8.

I am still amazed by the temperature debate surrounding Koi.
The rules are simple. 24C is optimum. Feed like hell. Koi are seasonal. In winter cease all feeding - the Japanese stop feeding, completely at 14C. Their Koi are grown in large bodies of water in summer - where the temperature rarely hits 30C - due to stratification of the water body (aerated ponds excepted).

Above 24 Bobby I think has it - feed what the Koi will eat. Above 28 we don;t feed at all. Too much ammonia, too little oxygen, too much O2 demand from the filters if there is a lot of ammonia present. Mass fish kills in summer are almost ALWAYS preceded by heavy feeding, thunder storms (which lower the atmospheric pressure) and not enough direct oxygenation.

Waterfalls, sorry Chris, will have a cooling effect in an order of magnitude by the square root of bugger all. Very easy to calculate and unless you have a simply massive thing with huge turnovers of several times a minute with super cold ambient air (which actually dictates water temperature with a far higher correlation) you are farting against thunder...

Ditto Maruis, William

Hopefully my cover will be up latest next week so I can feed more with less temp issues.
Their is no doubt that the eating patten of my Koi is seriously effected with water above 26C

My second pond with a shade cover and therefore lower temperatures does not have the same problem at all. They are eating non stop.