[Graham Surrey]

Hi all,
I have had Koi in my garden pond for approximately 15 months-I "inherited" them-a couple of quite large specimens (circa 18") and about 20 fish ranging from 6-12".
The pond is approximately 8 feet square and around 30inches at its deepest point. The pond contains the usual ornamental plants:

Juncus effusa, water lilly, marginal iris and oxygenating weed (elodea crispa).

I have followed the advise of the fishes previous owner, carrying out regular water changes-15% every 2-3 weeks, regular cleaning of the filter sponges and topping up whenever necessary.

About 3 weeks ago, the largest fish displayed signs of "going-off" its food-the fish exhibits no obvious external signs of disease and is not gasping for air near the surface. I have, however, witnessed the fish swallowing the koi pellets, only to immediately spit them back out again. I asked an expert for advice, he suggested it may be egg-bound and to carry on observing the fish.
The last few days, I have witnessed similar behaviour from a few of the other fish.
What could be causing this behaviour?

I have not added any chemical treatments or salt to the pond.

Please advise, as I do not want to loose any of these fish.

Kindest regards,
Graham.

[Davej]

Graham

Welcome to the forum.

The fish are telling you that something is wrong and you are right to try and establish what it is speedily as sorting things early saves compounding the problem.

First off you need to check the basic water parameters for Ammonia, Nitrite and pH, this will give you some clues as to whether it is an environmental issue.

If these don’t immediately identify a problem then there is a fair chance the issue is with parasites, there are various types which can from time to time cause problems for Koi, With parasites it is important to identify what type as the treatment that is needed varies.

You will need a skin scrape done, this involves taking a sample of mucus from the side of the fish and examining it under a microscope, you can see any critters that are on the sample. With this done you can treat accordingly. It is not a difficult task but you do need a microscope, your local Koi Dealer, Koi Club or BKKS Health Liasion Officer may be able to help you with a scrape.

Hope this helps

Dave

[Graham Surrey]

Thankyou Dave-much appreciated.
Would anyone know of a good person to deal with near Guildford / Aldershot?

Graham

[Doghouse Riley]

Hi and welcome.

We'd be better able to advise you if you posted a few photos.


From your description, the pond seems rather small for two big fish and twenty others, even with the water changes you've mentioned.
As has been said, something's wrong, one of the most common reasons for such symptoms is a high amonia content.
With the recent warm weather, I'd expect that the fish were eating well previously? But if the amonia level rises they go off their food straight away.
Koi secrete twice their own bodyweight in urine daily, so as well as the "poo" this could be building up the amonia and other toxic chemical levels.

When you say "filter sponges" do you mean those in a pump strainer, or is there a proper biological filter?


Has your pool an overflow?

My first instinct would be to start a "trickle change," just leave a hose trickling water in to the pool for a day or so, if you find that the safe parameters of the amonia, nitrate, nitrate etc., have been exceeded.
Don't do a rapid water change and lay off feeding any of the fish for a few days.

[Davej]

Agree with you DHR, but best to get a line in the sand readings wise first..

Graham, the first step in testing the water is very easy, simple investment three basic test kits for ammonia, nitritre and pH.

As an immediate step then as DHR suggests then changing a bit more water will be a good idea, but dont go too mad with this, and if they are not eager for food then dont feed them.

Dave