Koi Forum • Malachite Green removal : Koi Health


Thanks very much for the reply Kanundra. It is a bit of a long story really, I am building a new koi pond at the moment and This requires breaking up my old 7000 L garden pond. During the winter I also built a heated insulated 5,000 L pond in my shed and I have been building up the filters in that since about November. Finally now they seem to be getting it together after a long battle with Nitrate.

Anyway, starting my new pond build required me moving 4 fish out of the garden pond into the shed which were two about 10 -12″, a small little guy and a Golden Tench. The two bigger koi however were in a bad way. One has a bad case of carp pox on its tail which I have never been able to shift since I have had the fish (about 6 years) and the other one which is a white butterfly koi looks to me to be suffering from columnaris ( tips of fins look a little dodgy and is gasping a little to much).

I gave both of these fish a 10 minute salt bath at 22g P/L in 10L of water. The first one with the carp pox was bleeding a little from the big club of pox on its tail so I swabbed this down with malachite green and sprayed with Propolis and the white Butterfly was sedated yesterday and the same treatment with Malachite green to the fins and propolis was applied. I also checked his gills while he was sedated with an ear bud and they looked to my eyes to be ok. I did not see any mucus or decay thereor any spots of any kind. Having said that I am no expert on gills!

I had dosed the pond on Sunday with Malachite green because it was all that I had at the time as all the fish were swimming around with their fins clamped and they were doing the odd flick off the bottom. The Nitrite was coming down and around .3

Today the Ammonia is still at 0 and the Nitrite looks at about from between.3 and .1 from what I can read. I am delighted at last that is sorting itself out but I am thinking that a treatment of Formalin and Malachite green is the way to go as a good all round remedy. I bought a treatment from interpet called Medi-fin which seems to contain both these chemicals so I am thinking that is what it really what it is? I am aware too though of overdosing with Malachite Green which is why I am concerned about with how long it takes for it to disperse in the water and I can dose again.

I am going to hold off on that for a little while first and just see how things pan out first. The filters are only balancing out and I am mindful of upsetting them again at this critical stage with chemical treatments. I know some on here are not fans of salt but I am thinking that another series of salt baths for these fish might be a better option than dosing the whole pond again with more chemicals. But I am all ears for opinions from more experienced fish keepers on what I should (or should not) do.