Koi problem

[Wolvesfan71]

Hi I have an issue with a koi
He has been hiding a lot,not feeding and I have discovered this morning he appeared to have a growth on his head
Does anyone have any idea what this may be.at a total loss.water is Spot on

 

[GBBUDD]

Looks bacterial . Probably got a bump on the head and the water is not ideal. Just because our test kits say we are good does not insure our water is spot on.
If you test for kh what is it and if not I suggest you get one.

Proform c can kill bacterias but if the root cause is not determined it may come back

 

[WaterGardener]

Eyes also look milky. Is there fungus or excess slime coat on the lower side of the fish in the second photo?

 

[Wolvesfan71]

Hi,kh is 80,yes looks like some sort of fungus on side

 

[Mmathis]

What are the actual results of you water tests?

 

[Wolvesfan71]

I thought it maybe bacteria problem but not sure how to treat.can the whole pond be treated? The pond is approx 2000 gallons and houses 3 large golden orfe,2 koi,4 tench(small) and some gold fish the pond also has a large amount of plants, including Lilly,hornwort elodia crisps and loads of marginal plants.not sure if treatment will affect plants

 

[Wolvesfan71]

I regularly carry out tests,ammonia 0,nitrite 0, nitrate 0.i am assuming nitrate is low as plant are growing very well.pond water clear,no blanket weed