ulcer and red spots on my mature koi, first time ever. help appreciated.

[dutchstar]

this is my 2nd full season owning this pond. i have thus far been advised, and followed, a plan of minimal intervention in the biological workings of the pond, which has worked out great so far. i am in southeastern PA if that helps.

fish did fine over the winter, i kept a hole in the ice with a de-icer. they snoozed at the bottom of the pond and "woke up" just fine as it warmed up. i used Microbe-Lift Autumn/Winter Prep over the cold months, as directed, and I keep my pump shut off after the water drops below 55ish. i keep it covered with netting to prevent too much leaf buildup.

uncovered the pond at the end of march, cleaned out the debris from the upper waterfall weir, collecting pool, and stream. lots of sludge and one dead frog but that is about the same as what i found last year.

we had some good rains so that added to the water volume, and i added some faucet water (probably around 80gal) after treating with dechlorinating stuff and letting it sit for a while in a separate container.

fish have been eating and behaving normally, and looked fine until the other day i noticed one of our white koi has an ulcer on his side, approx 1.5cm diameter. then noticed that he had a few tiny red spots (don't appear ulcerated/inflamed, just red colored) on his skin and fins. small and scattered but not all over him. I looked at our other koi and i see similar marks on them as well. they all still seem to be feeding well and swimming around normally.

yesterday i tested the water, found no ammonia, nitrite, nor nitrate. (phew). i tested the pH and got the highest value (7.6) and then tested with the "high-range ph" test and got 8.4. this was around 4pm and it was warm and sunny yesterday around mid-70s. I had read online that the pH can rise at the end of the day, so i re-tested pH this AM (around high 40s) and got 7.8. i will confirm later on and tomorrow morning as well, to be sure.

i have tried to look up different koi diseases to find one that matches and haven't really found one. they still seem to be acting ok, they are feeding just fine. the pond has a lot more green string-type algae this year than last, which is the only significant difference i can identify. i have a UV sterilizer running so i'd think that should help - i may need to check that out as i had to re -silver the contacts this year but it was working fine when i put it back in last month.

I don't think that the algae overgrowth should harm the fish, but maybe flux in pH is related to this, and the pH is harming them? would it be wise to use one of these buffering products (pH down by pondcare/api for example) to lower the pH, such that any afternoon rise in pH doesn't stress them too much? microbe-lift makes a pH "stabilizer", maybe this would keep things within a normal range?

i'd like to identify the problem first before i start to attempt to intervene and treat the fish, but i also don't want to lose any of these guys, they are 13 yrs old, big and pretty, and our kids love them. but if everything seems ok with the water, what about treating with something like Melafix to help them heal? there are a lot of crazy looking products out there and i'm very wary of using new stuff.

there is a significant amount of leaf/organic debris buildup, and i have a service coming out in a few weeks to drain, clean, and refill the pond which hasn't been done in years. they don't use any chemical stuff, just water to clean, then they treat the hose water with dechlorinator stuff and add Stress Coat and more beneficial bacteria, and they take the fish out to a holding tank while they do. i'm glad this problem didn't arise AFTER they came, otherwise i'd be apt to blame them. i also wonder if i should hold off until i fix this health issue before i stress the fish more with the cleanout.

thanks as always for any input you may have on this. i'll try to get some photos of the fish as well.

 

[Dave 54]

My guess is that you have an aeromonas infection going on in the pond .
"Minimal intervention in the ponds working is a no, no.
The cleaning of both pond and filter medium are a must, sadly this infection has most problebly come about because of this Minimal intervention.
I dont know here you got that idea from but loose it remember maintenance is a must.....
We clean the filters and pond prior to the winter months but continue water changes throughout the winter period, using what is known as the trickle method of filling the pond.
Then kick start them with Microbe_lift Filter Pad innoculant gel.
Look into why your PH is in Flux and how your going to change it for the better i;e bicab of soda etc
This is where you the water trickles into the pond, then the ambient heat of the pond warms the water trickling in,
Now if this is done correctly then you shouldnt loose more than .1 - .2c try practicing it in your sink or bath if your unsure as to how you go about this .
As the spring approaches we clean both the pond and filters again ready for summer
If it is an aeromonas infection we then need to find out if the infection is gram positive or negative treating the fish with the correct antibacterial treatment .
A vet needs to be approached with a number of swabs to ascertain which is aflictiing your koi then giving you the correct treatment to treat them with.
Here in the UK we have a product called koi klear Gel which is a fantastic treatment in that its a mixture of herbs and ozonated Gel and really does what it says on the container please see link

:- http://www.absolute-koi.com/subcat2086.html

Sadly I doubt whether they would send just one order out from the UK it really needs to be a bulk buy nd at £25.00 for 5g it doesnt come cheap ( you'd have to arrange for a good number of others to be in on this ).
If the infection is in its advanced stages so may well prove difficult to treat however a good off the shelf bacteriacide normally works .
Deciding on which to use depends on the results of those swabs you sent to the vet it is also important to treat any secondary infections your koi may get .
It is suggested you inject the correct antibiotics after anethatizing your koi ( I'd ask your dealer to do this for you).
But remember to treat the ulcer/fungus etc with malachite and Propolis (you can buy this cheaper at a health store rather than spending extra at your dealers I use both the spray version and liquid.
If you have never heard of this before its a by product of a bees hive and which keeps healthy a free of disease it has the same effect on koi as well as golfish.
If you have lots of young koi in your pond it would be impossible to treat them all by injectihg them. So in this case the antibacterial treatment should be then soaked into the koi's food and fed to them over a number of days remembering to finish the course completely.
"Remember this for the future rain water isnt good for your pond, many people think great a water change on the cheap and out of the sky". .
"Remember prior to winter pond bottom clean and filter clean the same again in late spring maintenance is a must as are water changes throughout the year"
The best way of doing this is a net across the pond to catch anything falling into the water,especially in the fall or during storms, we use a 6mm hexagonal bungee strapped net which nothing apart from insects gets through.
Wishing you luck in treating your koi .

rgrds

Dave