Koi & Low Temperatures

[mark4785]

Hi,

I currently have 4 Koi within my pond. At present the temperature outside is around -5 centigrade at night time and it hasn't changed from this for around 5-6 days in the Derbyshire area. The temperature during the day is either 0 or going into sub-zero temperatures. The pond surface is frozen solid with ice and is covered with 5cm deep snow (I have now removed the snow to allow more sun light into the water; will this increase the water temperature slightly?). There is a hole in the centre of the pond where the aggitated water coming out of the water feature has prevented the water from freezing. Given these circumstances, should I be worried or expect some fatalities?

The pond has a depth of around 2.5 feet and all the water parameters are perfect. I've been adding a vitamin supplement throughout the cold months instead of feeding them any solids.

I would appreciate it if somebody with experience of koi-keeping can tell me if I'm doing the correct things.

Thank you.

 

[black angel]

being able to keep a small part of the pond from freezing over is the best you can do for your fish for now..they will sink down to the lower parts where the temperature will remain stable for them. koi are extremely hardy and unlikely to be phased by the cold temperatures. as for the additive i dont think this is necessary. you may need to have as a job for the summer to dig your pond a little deeper, koi like to be in ponds at least 4 foot deep

 

[mark4785]

It appears a small juevenile Koi has died within the pond, probably due to the temperature being consistently below zero both night and day throughout January. The rest of the fish appear to be fine (resting on the base and swimming slowly).

The Koi that has died is a white ogon, bought from Dobbies Garden World Aquatics department. It is the 2nd fish to die from that place; I don't know whether this particular species are bred primarily for their looks and less for their hardiness or whether the garden centre is to blame here.

I have provided a picture of the white koi below; is it alive with a buoyancy problem or does it look as though it has passed away? If it is indeed dead I need to have it removed .

Pictures:

1.)

2.)

3.) Other fish appear fine thankfully.

 

[mark4785]

being able to keep a small part of the pond from freezing over is the best you can do for your fish for now..they will sink down to the lower parts where the temperature will remain stable for them. koi are extremely hardy and unlikely to be phased by the cold temperatures. as for the additive i dont think this is necessary. you may need to have as a job for the summer to dig your pond a little deeper, koi like to be in ponds at least 4 foot deep

Thank you for the reply Black Angel.

I will consider that; I think that will be a massive task that will require help from my Dad and possibly vet as the fish may need to be sedated to avoid becoming too stressed. What is your opinion of pond heaters? Will it be more easy and practical to install a powerful heater for next winter or possibly this winter if weather conditions don't improve?

 

[black angel]

fish die for many reasons and no symptoms, dont feel too bad if it is dead.

i would heat my pond if i could but the cost is there. a swimming pool heater i think is the only way as pond heaters just radiate enough to keep a small patch open if it freezes, which may be all you need i dont know.

most losses occur through the winter anyway and my pond loks like an eskimos been in and fished lol. my ponds 4 foot deep so no way can i see whats happening down there but yours seem to be quite active.

 

[mark4785]

Cost isn't really an issue if I could be told of a specific heater that is suitable for fish and is statically known to prevent losses due to the temperature. My only concern would be if the heater failed or the weather caused a power outage which I guess are situations beyond my control. I personally think the species, the fact that it was young and the care it received where it was bred all contributed to this. My water parameters are fine, there are no clinical signs of parasitic/viral infections and I've applied a vitamin supplement throughout January that prevents anorexia. Maybe small koi of this species are not suitable for ponds especially if it hasn't been properly cared for prior to purchase.

 

[black angel]

Koi are the hardiest of all temperate fish and wont be phased by british winters..in japan they are kept in - conditions way below ours and are quite active through the winter months..I would be more concerened about the depth of the pond as the deeper it is the more stable the temperature is.
Breeding and genetics do play a part in how strong a fish is so maybe stay away from that type or place of purchase.

As for heating the pond it really is not needed for koi..if you had something like fancy goldfish then yes i can see the need but seasonal fluctuations arent a handicap and nearly all goldfish/koi can slow down their metabolism if needed and go into an almost hibernating effect.

Maybe someone else has a heated pool but Im sorry I cant help on that part...maybe build a summerhouse over it.

 

[mark4785]

Thank you for the reply again Dark Angel.

Me and my parents have managed to get a closer look at the white metallic ogon and it appears what is called blanketweed (long strands of green algae) had entered it's gills and the other end of it was poking out of it's mouth. The ogon and some orfe appear to be hibernating in this weed which is growing up all sides of the pond. We netted the ogon and pulled the weed out of it's gill and mouth; despite doing this it still was showing signs of swimbladder (it isn't able to swim and balance up right).

I don't know whether this has caused the buoyency problem or whether it had this to begin with.

I was hoping the blanketweed would use up some of the nitrites in the water but it appears it now kills fish?