Grey stuff on my fighter

[Sprinkle]

Hi all

When I got him first, he didn’t have this.
It started to develope couple weeks ago, I tried doing some water changes, but these seem not help.
I want to give him a salt water bath in one of my 5 L bucket.
How much table spoon of salts would I out in a 5 L bucket?

and here is that thing
(Its on his mouth and back of his head, grey, not bumpy, kinda making hole, a pit where scales kinda stick out and his mouth kinda eaten away but not really)

 

[the loach]

This looks more like a bacterial problem, a salt bath is not going to do anything I would just use the Artemiss you still have?

 

[Sprinkle]

Thank you Mr T the loach .
Yes, I still have artemiss luckily.

Today it became white, the stuff
(He no easy to make a pic of, i had to give him a flake so he has something to choke on)

 

[Sprinkle]

In second photo, you can see the thing on his mouth too. I’m thinking columnaris.

 

[the loach]

I'm afraid you could be right about that. For how many weeks did you have this fish?

 

[Sprinkle]

Why would show its self now? With perfect conditions?
To answer your question Sir, Mr T the loach , I had him since Nov 11 2020 according to my thread.

 

[the loach]

So like 2,5 weeks, which is still within the quarantine period. Shipping is hard on fish and these things do not show up immediately, regardless of water quality. That's why it is recommended to quarantine fish for at least a month, 3 months is better.

 

[Sprinkle]

I will do larger than 50% water change tomorrow. I add artemiss today Mr T the loach ?

 

[the loach]

Yes I would add that immediately. He is the only fish in there? I don't see the need for a 50% change if the water is "perfect" as you say. Is there a large difference between tap and tank water? You could do like a 15% change each day then add the Artemiss mixed with the new water.

 

[Sprinkle]

So I do a 15% water change now and after I add artemiss with new water? How many mls?