Koi continue to die

[Beckie]

I posted in August about my koi dying....the largest ones, around 10 years old, well-established appx. 2000 gallon pond. Several have died, in spite of a near perfect water balance, absolutely no signs of disease or injury. With all the rain previously, then a hurricane, we've had tons of frogs and toads mating in the pond. I did some research and it's possible, but wondering if poisonous toads (Florida) were laying eggs in the pond and the bigger fish were eating them? We started catching toads, and no deaths for a couple weeks.

(Side note: I thought at first they were getting stuck in the pump box as that's where I found most of them. Put a cage over the inlet (thanks for the suggestion!!)...then found one floating up against the cage.)

Just found my last original fish dead in the pond this morning. It showed no signs of illness or stress the night before. Anyone have any ideas? Any problems with poisonous toads?? Any suggestions?

 

[Gemma]

Oh Beckie I'm so sorry!
How many fish were there when the first one died? I'm thinking this could be the result of lack of oxygen, due to overstocked pond

 

[Beckie]

Oh Beckie I'm so sorry!
How many fish were there when the first one died? I'm thinking this could be the result of lack of oxygen, due to overstocked pond

I started years ago with only 5, had to dig a bigger pond when they kept having babies and ended up with 16! Lost 3 over the years to a dog, a bird, and one that had been notorious for getting in the pump box to get the last morsel of food. So, 13 fish in a big pond, 4 ft deep, 2000 gallons, and very good waterfall flow. Had the 13 fish for years and years, very well balanced pond...only this past few months have I had any problems. Down to 7 fish, so I've lost 6 in the past couple months.

Had water tested and it confirmed my results...great water quality. The fish aren't struggling or acting odd in any way the day prior. I find them dead. When I remove them from the pond I see no sign of disease or injury. I've had an incredibly healthy pond with fish all these years.

The only thing I've found is poisonous toads are a possibility. We've had some ugly ones hanging around, too. One looked similar to a Cane toad but didn't have all the features.

And why suddenly is this happening?? We have toads and frogs all the time.

 

[Gemma]

Is there a pond place where you could get an autopsy? That's how I found what was happening, when mine were suddenly dying, years ago
I hope you can figure it out and save the rest of the fish

 

[Beckie]

Is there a pond place where you could get an autopsy? That's how I found what was happening, when mine were suddenly dying, years ago
I hope you can figure it out and save the rest of the fish

Not that I know of...what did you find out about your fish?

 

[Tula]

Do you have a local koi club? If so, I'd contact them and see if they can help you. One of their members will have a microscope, and you could scrape and scope one of your remaining koi, to look for parasites. I've read that frogs can bring in parasites.

I'm so sorry you're going through this.

 

[Gemma]

My fish die from arsenic poisoning!
We built a bridge out of pressure treated wood to shelter the fish from the Heron, (we didn't know any better) every time it rained, arsenic leaked in the water
After the first few died we decided to pay for an autopsy, we then removed the bridge and changed all the water but still the damage was already done, and one by one all my fish died

 

[Gemma]

Do you have a local koi club? If so, I'd contact them and see if they can help you.
.

great idea! I'd check Facebook!

 

[sissy]

Have you checked the oxygen levels and were all the fish that died 1 sex .I have seen fish that have died from being egg bound from temps ,but since you live in a warm climate it is unlikely .Have you made sure nothing could have gotten in the pond that caused a lot of stress and have you made sure it is not an electrical short in a pump .

 

[CometKeith]

Beckie I'm very sorry about your fish. I would guess they died from lack of dissolved oxygen. These are my reasons; The hottest months like August are when the water is the warmest and there is the least saturation of dissolved oxygen. Typically overnight the O2 dips to the lowest levels and you found the dead fish in the morning. The largest fish died first and larger fish need more oxygen than smaller fish and are the most susceptible to this problem. Typically a fish that dies from lack of O2 doesn't show any other sign of distress or disease. I have seen a number of posters on this site that had successful ponds for many years and suddenly their biggest fish died and it was due to a lack of O2.
My understanding is the problem happens suddenly when the problem gets to a catastrophic level where fish die without warning. For all these reasons I think lack of dissolved oxygen caused the problem.

 

[Gemma]

I have seen a number of posters on this site that had successful ponds for many years and suddenly their biggest fish died and it was due to a lack of O2.
.

This happened to me, when I didn't know about overcrowding, and that's why I asked about number of fish in the pond, but one could have poor dissolved oxygen even in a pond that's not overstocked, so I would increase aeration just in case

 

[Magzire]

No aerator? Seems crazy not to have one

 

[Angel]

No aerator? Seems crazy not to have one

i didn't have one for 8 years no issues i added this year for winter. so aerator is not always needed

 

[Magzire]

i didn't have one for 8 years no issues i added this year for winter. so aerator is not always needed

But the koi got bigger consuming more or maybe the pond bio used up more. what else could it be at this stage?

 

[IPA]

Could it be stray electricity?