Urgent issue with koi health

[Dean little]

On Saturday I woke up to find two koi seemingly gasping and laying on their side, I also noticed some smaller gold fish at the top too. I immediately took a water sample did a 30% water change then took water sample to local shop for testing. The water sample came back with very good results. When I got home I increased the airflow to the water.

The fish settled but now all of my large koi are sitting on the bottom and very listless. I have treated the water today with broad spectrum bacterial treatment.

Does anyone have any other ideas? Should I also hit them with broad spectrum parasite medication?

I am a little confused I have had these fish for over 6 years and never had a issue, then over night I have been hit with these problems.

 

[Tula]

Welcome to the forum, but sorry for your fish troubles. People here will want more information about your pond and filtration, so they can better help you.

How many gallons? How many fish? What type of filtration? etc.

You did what I would have done, tested the water ( BTW, do you have exact numbers for ammonia, nitrite, nitrate, PH and KH ) and adding aeration.

 

[Dean little]

Pond is 427.62 gallons, I have an exterior sump filter for the pond (which is purposely too big for the pond). Fish - 5 medium Koi (45cm), 1 shabumkin (spelt wrong), 2 small very small butterfly koi and 4 gold fish (small).

I don’t have the reading from the test this was done at the shop near me.

From reading various website it seems it could be parasites? As stated I treated for broad spectrum bacteria today, now thinking I should have gone first with parasite treatment. I am looking for place to examine scrapes, but local outlets don’t offer this service

 

[Jhn]

Gasping at the top is usually due to low oxygen, ammonia poisoning. Watch treating your pond with chemicals especially if you can’t identify what is going on with your fish, as these can mess up the biological filter in your pond, exascerbating the problem.

Your pond is on the small side for koi, as they grow quickly and their accompanying waste production can overwhelm the filter in the pond, seemingly out of nowhere. As you have said the fish have been fine for years then all of the sudden overnight they aren’t. The fish keep growing and can reach a tipping point where your ponds filter system can no longer handle the waste being produced, which in turn causes ammonia to rise, which in turn inhibits the fishes ability to pull oxygen from the water through its gills.

How much does your filter turn your pond volume over per hour? Are there plants in your pond? Your readings should be ammonia and nitrite zero, in a healthy balanced pond, and the number on your ph isn’t as important within reason as it is the ph stays stable and doesn’t swing.

 

[Tula]

At 427 gallons, your pond is overstocked......too many fish. I agree with @Jhn , fish gasping at the surface is usually a sign of low oxygen, which as he pointed out , can result from ammonia burning their gills.

Any chance of enlarging your pond?

 

[Lisak1]

I am sorry that it's trouble that brought you here, but hopefully you can resolve this issue and stick around!

Your pond is WAYYYY too small for koi. We hear constantly that "everything has been fine for 3, 4, 5 years and now THIS happened". The difference is the size of your fish. They keep growing, but the pond stays the same. You reach a tipping point and there's no going back. The only long term solution is to reduce your fish load. You have a gold fish pond.

Sorry to give you bad news, but there's just no getting around it.

 

[Dean little]

Thanks for all the advice but since Saturday and the 30% water change - No fish have been gasping - they have since retreated to the bottom and now remain listless. Oxygen was my first concern and hence I addressed this, but still the issues remain. I take advice on size of pond and will reduce numbers giving away large koi, however, I can’t give them away in this condition.

I do find it difficult to understand how after 6 years these fish which have not grown significantly are now experiencing theses issues. I bought the house with this pond and fish already here. When I arrived you could not even see the bottom due to poor water quality (I did not even know there were fish in there) and only a small interior pump being used - they survived ......

If it is not water quality and oxygen - what could this be??

 

[Dean little]

apologies missed one question in thread of replies - do I have plants? - yes a water Lilly, two eleocharis, 1 myriophyllum and 1 hydrocotyle. For clarity I also replaced the interior pump with a bioforce reveloution exterior pump which is purposely too big for the pond (did this for years ago)

 

[Dean little]

Update - all but two fish seem to be doing better. Two Koi (one in particular) not swimming well and remaining listless.

 

[Tula]

I'm glad to hear there has been improvement. I understand you can't regime any fish in their current condition. By chance do you have a live stock tank, I purchased mine at a Tractor Supply Store. If so, you could put the smaller fish that are doing well in it and keep just the struggling fish in the pond.

Of course I realize it's an extra effort, but a simple filtration could be made if you have an extra pump.

 

[JamieB]

I’m inclined to think ammonia damaged that ones gills, which takes time and lots of good water to cure. If you have a place to set one up away from predators, a kiddy pool and air pump with a quick filter, start with pure pond water, adding fresh dechlorinated water every day just letting it deplace the old by 10-20%. Or a stock tank, something big enough to act as a hospital tank. Then, if you wish to keep the fish, enlarge your pond, and increase the filtration. With 7 koi and 5 goldfish, you’ll want to shoot for around 8000 gallons. If you do decide to do so, that can include something like a wetland or bog filters. I’m wondering if the larger koi have been stunted due to small space, as you bought the house with them, so no knowing just how old they really are. If you have limited space, you could do a raised pond, partially above ground, there are several articles on here about it, as well as online and YouTube.

 

[Dean little]

Thanks again for all the helpful advice really appreciated! Unfortunately due to the location of the pond I can’t enlarge so will work on giving the fish a new home.. I will keep changing the water more often to help flow of clean water into the tank and hopefully this will help... the two most affected are really bad one periodically floating on side before swimming again and the other propping itself in the corner face up. I have asked a few times but no direct response to the question. Do you think this could be parasites? All articles I read on the web seem to lead to this?

 

[Tula]

Without a scrape and scope there isn't any way to know for sure if this is parasites. If it was parasites, it would affect the other fish as well, so in my opinion it doesn't seem like parasites.

 

[CometKeith]

Thanks again for all the helpful advice really appreciated! Unfortunately due to the location of the pond I can’t enlarge so will work on giving the fish a new home.. I will keep changing the water more often to help flow of clean water into the tank and hopefully this will help... the two most affected are really bad one periodically floating on side before swimming again and the other propping itself in the corner face up. I have asked a few times but no direct response to the question. Do you think this could be parasites? All articles I read on the web seem to lead to this?

Hi. I'm very sorry for the loss of your fish. Typically a minimum of 1000 gallons is required for just one Koi. The fact that you had several large Koi plus other fish in less than 500 gallons is a recipe for disaster. If you can't enlarge your pond I would give away all your Koi as soon as possible. It's not unusual for catastrophic affects when the dissolved O2 becomes too low. Many people have come on gpf with everything good for 5-10 years and then suddenly all their Koi died because they were too large after many years of growth and the pond could no longer support them.

 

[JamieB]

With parasites, you typically see flashing, fish rubbing on things, or visible marks on them. I’d really suggest you set up large kiddie pools as hospital tanks for the two most effected. Add lots of airation, good filtration, and frequent water changes, and just observe for a while to see if they improve. This also lets you check them for inflammation of the gills, and you can look closer to see if you spot parasites. Now, by kiddie pool, we are referring to the large hard plastic kind, a depth of over 12 inches gives you a large surface area to depth ratio for good gas exchange, sides high enough to reduce chances of fish flopping out, and enough water volume you won’t risk killing it due to their own waste in a single day. Other options are the extra large plastic totes , bigger is better so long as you aren’t going more than 2ft deep, you want lots of gas exchange.