I wouldn't treat without due cause. malachite green is great but why dose the fish if they do not need it?. I know some dose as a preventative measure, I feel that this will lead to a lessening of the effectiveness of a product. Can you do a scrape and take a look under a microscope, or observe the fish over the next few days and see how they behave. What type of fish are they? How long have they been in q'teen at your suppliers? What have they been treated with at your suppliers before being offered for sale? The answers - (from your friendly supplier who, being a good supplier, won't mind telling you), all have a bearing on what you need to do. This is my own opinion, and I'm sure there will posts off others who will have their own way of doing things.

Hi aaron118,
Only one question? I've been keeping koi for three years and still have loads and loads of questions to ask. Mixing treatments or following one treatment with another immediately after is generally avoided. Malachite green is an exception to this in that it is usually mixed with formalin when used as an anti-parasite treatment. Malachite on its own is used as an anti-fungal and in small doses it can be used to stop koi spawning, so avoiding possible damage (koi contraceptive?). Quarantining new fish should be for at least two weeks, better for a month. The quarantine tank temp should be slowly raised to 23'c or warmer and held at that temp for a week or so to bring out any latent KHV that maybe in the koi.
Chris.

Why are you going to quarantine? I have never done this when I have bought fish for the pond. I have always used a pond treatment if I have introduced new fish into the pond. It is called Eradick and is also a five day treatment for fungus and parasites. I have never had a problem with it.
Alison

If you're buying koi, then there is the very real concern about KHV. We made a decision and only buy from the one supplier who we trust, they quarantine the koi for 3 months. I then introduce my new fish straight into the pond. We've had interesting debates with other koi enthusiasts, and there are many varied views. If your Q'teen facilities are not excellent, you could end up harming an otherwise healthy fish. >>KHV - First found in Israel in 1998 it is now found in most of the world. The virus attacks the immune system of the koi so the signs of the disease are non-specific. The infection attacks in warmer water between 18C and 28C and spreads through the water with a 90% mortality rate. Koi carrying the disease but showing no signs of ill-health cannot be tested to see if they carry the virus.

There is no cure for KHV, the disease will disappear at water temperatures above 30C but koi carrying the disease will continue to do so.

The best way to avoid KHV is to quarantine any new additions to your collection for 4 weeks above 21C

Yep, so unless you can heat a quarenteen tank theres no real point in having one, because it is the heat that brings out the problems, and in our climate that takes a long time to reach those temps naturaly.

As for malachite, never use it unless there is a specific reason to, treating healthy fish can cause them to be unhealthy, the same applies for all medications, so care is needed.

KHV can be prevented apparently, Israli koi farms are owned by the Israli govenment, so they underwent a vacination programe, so all koi bred since are immune to it, but the japanese hill farms cant afford it, so they dont, so unless as Linda says you dont buy form a dealer who quarentines fully every japanese intake you are taking a risk, never buy form a garden centre.

I read somehwre that there are some tablets on the market for it too, cant rememebr what its called tho, costs about £30.00 for a small tub, supposed to be the same stuff as the vacination, if it works then people with older fish (pre KHV era) can use them to protect thier koi.

agree with all of the above. I NOW ONLY BUY KOI FROM ONE SUPPLIER! and pond is officially full! no matter how good "that one looks" when we go for food lol if you want to look at the yks furum one poor lady has now lost her whole collection to a birthday present of koi from en ebay buy! my sympathys to her - note to self - advise family not to buy fish for christmas/birthday/fathers day etc jo o/

To add my 2p, I just bought 2 new koi form a local aquatic shop and both have spots on their tails, my other fish have always been healthy so I am worried it will spread.

Can someone recommend a good Koi dealer? I am in East London.
Is there a place we can search?

I'm in Hornchurch just up the road from you. I've bought koi from four local dealers, although I'm not overly impressed with any of them, I would say Koi logic at Upminster is the best of the bunch. They only sell Japanese koi from the breeder Ogata.

thanks Chris

PKingham, what sort of spots?

See this thread AJC
http://www.uk.gardenweb.com/forums/load/ukponds/msg0615442526491.html?12

Here is a link that might be useful: poorly koi

Yeah I saw it afterwards.