Help with mom’s pond please!!

[Tarheel05]

So to give everyone forewarning I know little to nothing about ponds. My parents have a koi pond that is approximately 5 years old. My Mom had several koi and comets. They were approximately 2-3 years old. I would say she had around 30 fish total (they had reproduced also). She recently bought a new koi and some new plants to add to her pond. Well within a month her fish started dying off. She suspected a parasite and got treatments but the majority of her fish died.

Long story short, she was very attached to these fish and pretty devastated. My parents are out of the country on a trip they have been planning for a few years. When they left a week ago there were two fish left. A large koi and a comet. Someone had been by to feed the fish and add parasite treatment. I live 20 minutes away and have two small children so only went out to check on things today.

I immediately noticed an awful stench when I got close to the pond. I looked in the filter and her large koi was dead in the filter, thousands of maggots coming out. I pulled the filter out and disposed of the dead fish. I did however see the last fish swimming around in the pond.

So for some reason my mom’s normally very clear pond is green. Very green and murky. I could barely see a foot into the water. The pump appears to be working and their waterfall is on.

Is there something I can do to clear the pond up before they come home in a week and to help save the last fish? I just hate for her to come home to a total disaster but I don’t even know where to start. It would have to be something fairly simple based on my skill level and family schedule....

Thank you in advance!

 

[addy1]

Welcome to our group.

So sorry to hear about the loss.

My best guess is the dead koi put a lot of nutrients into the pond, it will take time for the filtering system to clean it up. Also tell whomever is feeding to stop, there may not even be a fish left, if there is it will be fine without food.

My other guess is the fish she bought was sick and infected her pond.

 

[poconojoe]

It's difficult for us to diagnose the problem without knowing the history, size of the pond, water parameter readings, type of filtration, plants, oxygenation, etc...etc.
Pond fish need the water to be oxygenated. This can be accomplished with an aerator or just splashing or fast moving water.
It could be the new fish introduced something bad. Maybe some chemicals leached into the water. Maybe the ammonia level got too high from too many fish. The Ph could be off. The water parameters have to be checked. A test kit will be needed for that.
Perhaps a partial water change would help. If your tap water is treated with chlorine, you will have to add a dechlorinizer before you add fish.

 

[j.w]

So sorry for your mom's pond and fish.
So you took out the filter and cleaned it out w/just water right? Then put it back in and all is working fine now right?
I think w/all the fish that died you may need a partial water change to start with and then see how the remaining fish react. You would need to have a pump in the pond w/tubing or hose attached to get the old water out as you add new clean water. Better to do it slowly so it does not stress the remaining fish. Slow water in and slow water out.

 

[Jhn]

Agree with the others, This is one of the few times I would advocate a water change, to dilute the chemical that was dumped into the pond to treat the fish. As was mentioned get Prime or some other type of dechlorinator, if there is chlorine in the tap water, otherwise it isn’t necessary.

Did your mom actually identify the type of infection that was killing the fish? Did she know the exact volume of her pond? These are very important factors when dosing treatments, if you don’t know these factors, treating the pond with a chemical can cause more problems than what it is supposed to fix. IE, overdosing the treatment wiping out the biological filter of the pond causing ammonia levels to spike, reducing oxygen levels which in turn can cause massive fish die off.

Outside of a water change do not add anything to try and clear up the green murky water. I like j.w.’s suggestion of a slow water change pumping old water out as new water is coming in. The pond was thrown out of balance with the parasitic treatment and dead fish. Once these are removed or allowed to dissipate over time the pond will balance itself out again and the water will clear on its own. Also, make sure the friend or neighbor doesn’t dose the pond again with the parasitic treatment or as abby1 said feed the remaining fish.

 

[Tarheel05]

Thank you so much for all the responses! We have stopped feeding the fish. I am headed back out there today to check on the one remaining fish. I have not put anything in the water at this point. I was able to get in touch with my Mom and she said to add something to the water she has to make the green slime go away. I am not sure what it is but based on your advice I will not add it probably. She has some barley rolls and I will remove those too.

I am not sure she was ever 100% sure what killed the fish but suspected a parasite. She had some trouble with the ph level when she first had the pond and wasn’t able to keep fish alive. She got it worked out though and I think would have checked that first. She has well water and not tap water so chlorine wouldn’t be an issue.

I will pass on all your advice when she gets home. I am not sure how to drain the pond so I will just hope it clears up some soon!

We have had a spike in very warm weather recently too so maybe that is part of the problem. Thank you again!!!