Hi, Im new to Koi and could really do with some advice

[Pinknelly]

Hi everyone,
I inherited a pretty large pond 35 x 15 x 3.5 ft. six years ago. It's really established. It has a large filter, a waterfall for air which runs on a circular system with a satellite and several large water lillies. I have always had goldfish and small black carp along with newts, frogs, toads, snails and anything else you can think of.

I recently added a few Koi of various sizes, nothing huge, the largest was about 12 inches. They seem well really settled and happy, feeding well. I have also added about 50 small goldfish recently, in batches of 10 at a time.

Suddenly over the last week or so, the gold fish and black carp have started dying. Sometimes I find one a day or sometimes more, one horrid day I found 8. They have no fungus visible and in fact they look healthy, if you can say that about a dead fish!

I have tested the water and all marker including ammonia, nitrates, chlorine etc are good. Its not too hot in the UK. I guess if it was air then the larger fish would suffer first but they are really fine.

Could it be the food?
I wonder about insecticides from nearby farms?
Bacteria?

One thing I have noticed is that some of the goldfish seem to have lost their pigment. They started off a very bright orange but one or two have gone white. Not fungus, just white, like they have been washed.. That's odd isnt it?

Any suggestions would be welcome.

The pond is 10,000 gallons so I don't think i'm over stocked and I don't think I stocked too quickly.

 

[dieselplower]

All I can tell you is that it is not uncommon for goldfish to change color and it is also not a shock to me that many of the goldfish have died. Were these cheap feeder goldfish from a pet store? They are often pretty much half dead before you even buy them. You may well have introduced a sickness into the pond which has now hit the black carp as well.

 

[Pinknelly]

Thanks for your reply. I am afraid they were the cheap goldfish from a pet shop. I am really worried that I may have introduced something nasty to the pond. I guess without any clear evidence to identify a bug I will have to wait and see what happens. I won't add anything until it stabilises again.

 

[Lisaebetten]

#1 thing I have learned from this site in my 2 short months here is Quarantine Tanks are a MUST!!! Feeder fish and minnows aren't kept in good conditions as their main purpose leads them to a short life span. I'm getting ready to cycle my pond and am getting minnows that I will QT for a week before putting in my new pond. I just want to know what is killing them, my water or the bad water they had before me. Hope it works.

 

[j.w]

Pinknelly
Before I add any new fish to my pond I like to quarantine the new ones in a tank or tub by themselves for a few weeks to see how they survive. I'm wondering if the last batch of fish you added may have had some disease as diesel suggested. Not sure how you can treat if you don't know what it is. Sorry you may have just learned a good lesson on what not to do if you have to start all over again from the start. We all make mistakes and if we learn from them then all for the better. Just sorry you have to go through this.

 

[max384]

Did you quarantine any of the fish first?

When I started my first pond, I added about 20 feeder goldfish. About half survived, and most here said I didn't do too bad with only half dying...

 

[dieselplower]

Did you quarantine any of the fish first?

When I started my first pond, I added about 20 feeder goldfish. About half survived, and most here said I didn't do too bad with only half dying...

I also threw in 20 fish and 11 lived. So half is a common ratio it seems

 

[sissy]

could be 1 of those fish was sick and goldfish change color all the time

 

[Fishylove]

Welcome pinknelly glad to have you here. We would love to see pictures if you can upload them. I agree with everything above. A question about oxygen though, I know you say you have a waterfall but do you have plenty of mixing, ie: does the water stir in all parts of your pond? Also algae, even carpet algae, will suck the oxygen from a pond at night. Do you find the dead gf in the morning? Just a thought.

 

[Tula]

My pond is nay 1700 gallons, but I have a waterfall and the filter return line splashing into the pond. Additionally I run a large aerator . You pond is large, it's possible you may need more O2.

 

[Becky]

Hello and welcome aboard! Where abouts in the UK are you?

 

[Pinknelly]

Did you quarantine any of the fish first?

When I started my first pond, I added about 20 feeder goldfish. About half survived, and most here said I didn't do too bad with only half dying...

Oh crikey, no, I didn't even think about quarantine. I just put them in. Found another one yesterday. nothing today so far...

How long was it before your's died? mine have been in about a month or so.

 

[Pinknelly]

Hello and welcome aboard! Where abouts in the UK are you?

Hi, I'm in Shropshire.

 

[Pinknelly]

#1 thing I have learned from this site in my 2 short months here is Quarantine Tanks are a MUST!!! Feeder fish and minnows aren't kept in good conditions as their main purpose leads them to a short life span. I'm getting ready to cycle my pond and am getting minnows that I will QT for a week before putting in my new pond. I just want to know what is killing them, my water or the bad water they had before me. Hope it works.

Hi, I think you are right. a few people have talked about quarantine. I will definitely think about that in the future. I am just biding my time now and waiting. I hope this stops soon.

 

[Pinknelly]

could be 1 of those fish was sick and goldfish change color all the time

Yes, one of them could easily have been sick.
When you say goldfish change colour all the time, do they really? these have undergone a dramatic change from bright orange to white, but they don't just change overnight, some have faded down all over, others have faded in patches, some patches are still orange but others are white. They almost look like albino fish.
I heard tale of ruthless sellers dying fish. I know for sure they dye fish in china because I have seen it. Could it be that?