Soragoi turning brown on head

[Pinnacle]

Guys,

Can anyone tell me why my Soragoi has gone from a nice blanaced grey (2 weeks ago) to the next picutre which has brown patches on his head?

This seemed to have happened in the last two weeks.
I have had a couple of koi lunking and a few flashes, but I have taken many scrapes and can not find any sign of parasites.

Pond details:
PH 8 (tested at vrious periods and is stable)
DPD4 = negative
Ammonia <1
Nitrite 0
Nitrate 20

Heated to 16 degrees over the last 6 months.
Pond has a pergola cover with reed screen and polycarbonate.

Filter set up as follows:
Bottom Drain -> Nexus 300 -> pump -> 55w UV -> Heater -> mid water returns
Skimmer -> pump -> polybead 4 -> mid water returns

Air:
Pond has a medo 120 lt air into the nexus
Bottom drain (spindrifter) has 75ltr running.

Pond is 3000 gallons and 7' deep.

2 weeks ago:

Sora.JPG (58.17 KiB) Viewed 2310 times

Now (sorry picture taken in the dark):

Sora_brown.JPG (9.96 KiB) Viewed 2310 times

[Gazza]

Hi,

You say this has changed over two weeks is this a new fish or been moved

[Pinnacle]

Hi Gazza,

No this koi has been in the pond for a year.
Nothing has changed in the pond at all.

[Gazza]

Hi,

OK so its not that and all water is OK i take it so that should be OK.

Did you feed over winter and or have you just started to feed and is it the same food

How long have you had the fish and what is the breeder

[Pinnacle]

Breeder is Maruhiro from Gatwick koi.

Have been feeding over winter at 16 degrees, but pond has been covered until about 4 weeks ago.
Same food brand and type.

[Gazza]

Hi,

Depending how much food being fed and type this can also change the colour on fish but so does the water as some fish will darker up in water with a higher PH than they are used to,a bit like some fish go dark as they get older.

[Pinnacle]

This is such a shame as I really liked the purity of this particular koi. I always thought that the head of the koi is unlikely to change. None of my other koi seems to be effected.

So I'm assuming that there is no going back from this

So is it now classed as an Ochiba rather than soragoi ?

[Manky Sanke]

This one had me interested and I thought the answer might be due to genetics but I think Gazza may have hit the nail on the head with the pH being a possibility because high pH tends to imply a high GH.

Colouration is a hotly debated subject but most informed opinions seem to agree that high GH water promotes the production of melanin in the chromatophores (skin pigment cells) and melanin is what causes black or brown colouration. The next bit to the debate says that koi can't naturally synthesise melanin, it has to come through their food, not necessarily as "contains x% added melanin", but food that contains general colour enhancing additives.

Nothing in that is conclusive proof as to why the brown is appearing but one thing you could try is to switch to a basic wheat germ food for a couple of weeks to see what happens.

[Pinnacle]

Thanks Guys,

I'll get some wheatgerm in and update in a months time to see if this has helped.

I do have both a high GH and KH so without RO I can't see this changing in the near future.
We intend to move an some point in the next few years so I know for sure that on my next pond I will install RO.

[Gazza]

Hi Stu,

RO is not always the answer as there is a lot of it in genetics and food i messed about with some foods for a good few years and some had a big impact on the colours in the fish and some made them very fat.

One thing i found is that if you change food you need to stay on it for a good season and the foods from Japan which unfortunately none of them are cheap seem to be better quality.

[Pinnacle]

I'm not sure if my eyes are playing tricks on me but the brown on the head appears to be fading.
I've not switched to weatgerm yet and I haven't done anything recently that's any difference.

It is possible that the brown may have been somelike like bruising that is now starting to heal.

I'll check again this weekend and take a few pictures over the next few weeks so I can compare and see if the brown is actually fading or I'm just getting used to it.

[Gazza]

Hi Stu,

It could be a bruise as a fish will mark up if it bashes itself so will be a good idea to keep an eye on it.