New Koi owner concerned about black raised spots on back

[Jaspan71]

Hello, I’m new to owning Koi and I just added 5 into my 1500 liter pond over the weekend and today after they had acclimatized to the new environment, I noticed one of the koi had two raised black spots on the top of its back, all the koi come from the same farm, so I’m thinking its scales got damaged on the trip home, never the less I have quarantine the koi in a small tank with salt and treated the water with "Nitrofurazone" and "Sulfamerazine Sodium" a Japanese bacterial treatment for koi,

[Noahsnana]

Are you able to catch it to see if the scales are raised?

[Jaspan71]

Yes the scales were raised, however they came off when I relocated the koi in the quarantine tank,

[Jaspan71]

When I got the koi home the spots were white and I thought they were damaged scales

[Jaspan71]

[richtoybox]

I think that you are right about them being sites of damaged scales. It is a fairly common occurrence with netting. Keep an eye on it and if it gets worse, or spreads then worry, but for now, good water is the best medicine.

[Jaspan71]

Thank you for your advice and comments,

[aquaholic]

Welcome to the forum and to koi keeping.

There isn't any benefit to quarrantine since all your fish are new from the same source.
Quarrantine for several weeks - months is highly recommended when introducing new fish to protect your existing disease free fish.

Also there seems to be general agreement that 1000 litres (250 gallon) of pond volume per koi is a good guide especially if your inexperienced. I am usually at 5000 litres per fish myself (unplanned) but I prefer very low maintrnance - happy - healthy fish.

[Jaspan71]

Thank you for your feedback and advice, yes, I heard the same thing about the koi to water ratio, I plan on raising the pond level next summer, to compensate for the number of koi currently in the pond (5) I have also installed an oversized Takara Water Cleaner which was recommended by a local Japanese koi breeder,

[aquaholic]

That's good, but I would start on the upgrade sooner rather than later to prevent stunting and density related complications.

Go one meter ( 3 foot) deep at a minimum for Koi but 2m (6 foot) or 2.5m (8 foot) is better.

You will need larger volume water changes to keep your fish happy but you don't want to change a big percentage of your total water quickly to reduce sudden stresses like temp, hardness, pH etc so the bigger pond water volume becomes necessary.

A constant water flow/water change may be possible if your source water is consistent.

[Jaspan71]

Thank you for your feedback, unfortunately I’m limited with the expansion, as I’m working with an existing stone/concrete pond which was built 50 year ago, it’s seems that a lot of residential pond in Japan are very shallow, 30cm to 50cm from what I’ve been told, this is for safety “drownings” however over the weekend I increased the pond to 45cm/65cm, so basically I have increased the water capacity from 1500 liters to 2400 liters,

[Jaspan71]

[Jaspan71]

[Noahsnana]

Beautiful pond

[john s]

This looks like it might be "brown spot disease". If so, the dark spot in the cyst is a Digenean Trematode, a type of fluke or flatworm. Digeneans begin their life cycle in mollusk, often a snail, then proceed to one or more secondary hosts to complete their life cycle. Eradication can be lengthy and expensive using fluke medications and excising the cysts. Prevention is best way to avoid. What is your water source? Were the koi infected when you acquired them? Other secondary hosts such as animals and birds could transmit the Digeneans.