Lost fish 3 months into hibernation

[MermaidTracy]

Does anyone know why my fish would perish over a two month period? They were shubunkin goldfish and this was going to be their 4th winter. It hasn't even been cold. They didn't all die at one time. I was reading about maybe dissolved oxygen issues but I never experienced that before. I constantly run the pond filter. I'm pretty devastated. I have to start over in spring but i would love to know what happened Any clues?

 

[Stephen Noble]

Welcome to the forum MermaidTracy. Sorry to hear of your loss. How large is your pond? What type of filtration does it have? Did all of the fish die? What climate zone are you in? You mention that it has not been cold so you must live in Key West or San Diego to have gotten through the holiday season without any really cold days. Perhaps your fish have grown large in four years and the pond was not able to handle that much bioload. Have you tested your water parameters? Do you have many plants in the pond? What about a heavy algae growth? Could yard runoff be flowing into your pond and poisoning your fish? What is your water temperature? If you have fish, are you still feeding them? I realize I asked a bunch of questions, but it will help the forum members assist you if they are answered. Again, welcome to the forum!

 

[MermaidTracy]

I will try and answer all your questions. I have a 6 ft by 3 ft and 24 inches deep approx 225 gal maybe more. I have an oase filtration system with a waterfall. I had a total of 5 fish that I've had for almost 4 years. I got them small and they were about 10 inches long except for the goldfish who was smaller. They all perished within 2 months of each other one by one not all at once. I live in nj but this winter has been mild compared to blizzards they have all been thru. I do keep a deicer in during winter. I had many lilies this summer and kept them manageable. I did however leave them in this year until they died which is the only thing I have ever done differently. Water has always been clear and I have a healthy eco system with apple snails and frogs. I do not feed them in winter as it's not suggested below 50°. I feed them spring/fall mix in fall and spring and summer food in warm months. No runoff is getting in pond. I can't figure it out aside from either a parasite/infection or dissolved oxygen issue

 

[MermaidTracy]

Here is my pond this past summer

 

[Lisak1]

Very pretty pond!

The one thing that changes that people often neglect to consider is the size of the fish - they grow bigger, but the water voumne and filtration stay the same. The difference in the waste produced by a 2" fish and a 10" fish is exponentially larger - not five times, as one might expect, but actually more like 95 times more... it's wild. Here's a chart I frequently share that gives the details:

Koi Length and Weight - Ammonia Produced, and Waste Produced

This chart also lists koi weight by weight and how much ammonia and waste they produce. Koi get heavier as they grow and produce more ammonia and waste.

russellwatergardens.com

Your pond is small, which makes if far more susceptible to any kind of change - temperature, oxygen, amount of filtration, infiltration by outside contaminants, etc. The fact they died one by one is a clue - probably not a poisoning event, but more likely a water quality issue. When the weather cools, fish also become more susceptible to all kinds of things. The decaying plants in the pond may have been the issue as well - with nothing to consume the nutrients from the decaying organic material, the water could have become toxic for the fish.

Do you do any water testing? Could you see any signs of illness or damage on the fish before or after the died?

It's always distressing when you lose fish - we've all been there - but sometimes you just don't know.

 

[MermaidTracy]

I appreciate your thoughts. My fish have been large and very healthy for 3 years. They grew fast and wintered well. In essence only 4 were large in size since the 5th one was a chubby goldfish. I am inclined to think it was the decaying plants as I never left them in that long. Would a disease take them one by one? None of them had evidence on the outside of anything wrong

 

[MermaidTracy]

Also they weren't koi they were shubunkin so they reached their full size two years ago. I purposely stayed away from koi due to size

 

[GBBUDD]

Smart on no koi.
Nice little setup you have.
I'm wondering it it might be a ph crash we have had a ton of rain this winter and with no help from bacteria plants and microbes. It's possible your ph may have dropped along with your kh and gh . O2 is certainly a possibility. Where it has not been that cold this year my fish here in ct have been very active in comparison to previous years. If you shut the pumps down. And use only a breather it's possible there activity above and beyond normal for this time of year may have taken them out. Stripping the o2 If the largest fish went first then the next that would lean toward the o2.

 

[MermaidTracy]

I never shut the pump down. Even now with no fish it is still going. I want to keep it that way for frogs and also for a when I start over in spring. I thought rainfall acted as a water change and also added oxygen? Ugh so complicated I may never know. All shubunkin were the same size. Smallest was goldfish and he perished 2nd to last. I'm so devastated

 

[MermaidTracy]

Is there a way to test oxygen levels?

 

[Arielle]

Does anyone know why my fish would perish over a two month period? They were shubunkin goldfish and this was going to be their 4th winter. It hasn't even been cold. They didn't all die at one time. I was reading about maybe dissolved oxygen issues but I never experienced that before. I constantly run the pond filter. I'm pretty devastated. I have to start over in spring but i would love to know what happened Any clues?

It happened to my koi fish also, so I put 2 aerators in the pond so they have a lot of oxygen and I also put a good pond heater, so far I haven’t lost any fish yet , my fish looks happy and very active.

 

[Mmathis]

If you haven’t already done so, please test your water for ammonia, nitrates, nitrites, pH. You can get a test kit at most pet stores or order online. Whether it’s oxygen or not, it most likely is going to be an issue of water quality. These things can creep up on you……and unfortunately, it’s part of the learning curve. As someone else mentioned, even if nothing changes in your pond, the fish will grow, and as they grow they contribute an increasing amount of waste into the system — sometimes the biofilter just can’t keep up.

 

[MermaidTracy]

It happened to my koi fish also, so I put 2 aerators in the pond so they have a lot of oxygen and I also put a good pond heater, so far I haven’t lost any fish yet , my fish looks happy and very active.

 

[j.w]

@MermaidTracy

 

[MermaidTracy]

Thx Arielle, I'm sorry you went thru it too. I'm thinking next winter when I have new fish to do same bc you just never can predict weather